Contents
  1. Part I — Fitness is a contract
    1. Fit for which use?
      1. The same collection, different contracts
      2. Requirements, not a score
    2. Turning points in data curation
  2. Part II — Know what entered the dataset
    1. Origins, times and permitted use
      1. Times answer different questions
      2. Eligibility is separate from origin
    2. Population, frame and sample
      1. Selection serves different purposes
      2. A small coverage audit
    3. From summaries back to records
      1. Three complementary inspections
      2. A statistic is a pointer, not a verdict
  3. Part III — Preserve meaning
    1. Cleaning is semantic
      1. Unknown is not zero
      2. Filtering selects a population
    2. Duplicates depend on identity
      1. Similarity proposes; identity decides
      2. From exact copies to candidates
    3. Separate related information
      1. Match separation to the claim
  4. Part IV — Labels are claims
    1. Specify the label
      1. A label specification
      2. Convenient targets can answer the wrong question
    2. Disagreement is diagnostic
      1. Why 90% can mean little
      2. Resolve the cause, not only the vote
    3. Automate without surrendering review
      1. One record, several sources
      2. Suggestions alter reviewer behavior
      3. Selection has blind spots
  5. Part V — Release and maintain evidence
    1. A release is a dependency graph
      1. Recipe and state
    2. Data checks are not system success
      1. Two evidence contracts
      2. Controlled comparison
    3. Maintain fitness through change
      1. Compare releases explicitly
      2. Detection is not propagation
      3. Close the loop carefully
  6. Check understanding
  7. Open questions
  8. Selected talks
  9. References
  10. Talk library
← All topics

Data Quality and Curation

Data quality is not a property a dataset possesses in isolation. It is a relationship between evidence and a use. A collection may be excellent reference material for answering current policy questions yet unsuitable for training because its permissions forbid that use. A visually diverse image corpus may suit a creative generator while failing a product-catalog task that demands accurate identifiers. Even a perfectly formatted dataset can be stale, unrepresentative, mislabeled, or contaminated by information that should have remained held out. Data curation is the engineering work of deciding what enters a dataset, what each record means, which transformations are permissible, and how those decisions remain inspectable as sources change. The work begins with a contract: the task, operating conditions, unit represented by each record, and consequences of missing or misleading information. It continues through collection, inspection, cleaning, deduplication, splitting, annotation, release, and maintenance. Passing those data checks establishes that a release meets its stated requirements. Only independent evaluation can establish whether a system using it becomes more useful.

Part I — Fitness is a contract

Fit for which use?

A dataset is a collection of records selected for a purpose. A record might represent a document, transaction, image-caption pair, patient encounter, conversation, or completed task. The unit matters because rows are not automatically independent observations: ten messages from one conversation differ from ten conversations, and ten revisions of one document differ from ten independently written documents.

Start by writing the use contract. State the decision or behavior the data supports, the conditions in which that behavior will run, the unit of observation, and the cost of omissions or misleading values. Also state the dataset’s role. Training examples influence learned parameters; reference material is consulted at application time; reserved examples test a choice without participating in its construction. A collection suitable for one role does not inherit suitability for another.

The same collection, different contracts

UseOne record representsConsequential requirementPossible failure
Creative image trainingAn image paired with descriptive supervisionStylistic and concept coverageA conventional aesthetic filter removes intentionally low-fidelity styles
Current policy retrievalA versioned policy documentAuthority, permission, and freshnessA correct but superseded document supports a stale answer
Held-out system checkAn independently reserved task and reference judgmentSeparation from fitting and selectionA near-duplicate in training makes apparent generalization ambiguous

Requirements, not a score

This contract turns “quality” into separate requirements. Validity asks whether a value obeys its representation rules. Accuracy asks whether it correctly describes the intended thing. Completeness asks whether required values or cases are present. Consistency asks whether related representations agree under declared rules. Relevance asks whether the information bears on the task. Timeliness asks whether it is current enough at the decision point. A valid date can be inaccurate; a complete record can be irrelevant; an accurate fact can be too old.

Some requirements apply to each record, such as a recognized unit or a nonempty identifier. Others apply to the collection, such as coverage of a rare but consequential condition. Write explicit accept, review, quarantine, and exclude rules where the task supports them. Do not collapse the rules into a single quality score: an average can hide a fatal weakness in the one dimension the task depends on. Dataset size is a resource, not a substitute for correctness, coverage, or freshness.

Turning points in data curation

Data curation did not begin with foundation models. Its responsibilities accumulated through several technical traditions. In 1934, Jerzy Neyman contrasted probability sampling with purposive selection that merely looked representative, showing why the selection procedure matters to assessable uncertainty. In 1969, Ivan Fellegi and Alan Sunter formalized record linkage decisions among links, non-links, and unresolved pairs, separating similarity between records from identity of the thing represented.

As web collections grew, Andrei Broder’s 1997 work used compact sketches to make near-document comparison practical at crawl scale while warning that resemblance is not transitive. The March 2018 Datasheets for Datasets proposal made purpose, composition, collection, processing, intended uses, distribution, and maintenance explicit release concerns. DataComp-LM in 2024 then framed large-model data selection as a controlled experiment: hold the training recipe fixed, vary filters or mixtures, and compare the resulting systems. These contributions address complementary problems; later work did not make sampling, identity, or documentation obsolete.

Turning points in data curation

  1. 1934Neyman sampling frameworkMade the selection procedure—not a sample’s plausible appearance—the basis for assessable uncertainty.Sources & context

    Contributors: Jerzy Neyman

    What changed: Neyman contrasted stratified random sampling with purposive selection designed to resemble known population characteristics. His analysis showed that matching selected averages need not preserve other quantities or distributions, establishing why curation must document how units became eligible and selected.

  2. December 1969Fellegi–Sunter record linkageSeparated similarity evidence from decisions that records identify the same entity, event, or object.Sources & context

    Contributors: Ivan Fellegi and Alan Sunter, Dominion Bureau of Statistics

    What changed: The framework distinguishes links, non-links, and unresolved pairs requiring review. It explains why similar attributes can belong to different entities and differing records can still describe one entity.

  3. 1997Broder document resemblanceUsed compact sketches to make near-document candidate comparison practical at web-crawl scale.Sources & context

    Contributors: Andrei Broder, Digital Systems Research Center

    What changed: The work applied shingling and compact document sketches to an AltaVista crawl. It also emphasized that resemblance is not transitive: adjacent revisions can be similar even when distant endpoints differ materially.

  4. March 23, 2018Datasheets for DatasetsMade purpose, composition, processing, intended uses, distribution, and maintenance explicit release concerns.Sources & context

    Contributors: Datasheets for Datasets working-draft authors

    What changed: The working draft proposed dataset documentation modeled on electronic-component datasheets. It framed construction, appropriate uses, and limitations as information that creators should communicate to downstream users.

  5. 2024DataComp-LMHeld the training recipe fixed while varying filters and mixtures to test curation choices.Sources & context

    Contributors: DataComp-LM team

    What changed: DataComp-LM treated dataset selection as a controlled engineering comparison. Fixing a scale-specific training recipe made downstream differences more attributable to filters or mixtures instead of simultaneous changes in data, architecture, and compute.

Notice the progression from assessable selection to identity decisions, scalable resemblance, dataset documentation, and controlled curation comparison. Dates are chronological; spacing is not to scale and does not imply causal influence.

Part II — Know what entered the dataset

Origins, times and permitted use

Provenance records where information came from and the circumstances under which it was obtained. Useful provenance identifies the source, collection mechanism, source version, original context, and relevant times. A measurement made directly by an instrument, an event emitted by an application, a record contributed by a user, and a document acquired from another organization have different observation processes and therefore different omissions and assumptions.

Times answer different questions

FieldQuestion answeredWhat it does not prove
Observation or event timeWhen did the described event occur?That the record arrived then
Collection or processing timeWhen did the pipeline handle the record?That the event occurred then
Validity intervalWhen was the assertion considered applicable?That it remains true outside that interval
Source versionWhich particular source state supplied the record?That a changing “latest” resource still has that state

Operational logs are evidence of what instrumentation recorded, not a complete account of reality. A missing event may mean the event did not happen, the producer failed, the collector was unavailable, or a permission boundary hid it. Preserve absence reasons where the domain supplies them rather than reducing every missing field to the same blank value.

Eligibility is separate from origin

Traceability does not establish permission. A source can be accessible yet restricted from training, redistribution, or a new commercial purpose. Attach relevant permissions, prohibitions, sensitivity classifications, retention limits, and customer boundaries to the source or record, then consult them during selection. The Privacy and Data Governance chapter develops the policy, access-control, deletion, and accountability mechanisms; curation owns the narrower question of whether a record is eligible for this dataset release.

Population, frame and sample

The target population is the set of situations the intended claim concerns. The collection frame is the set the collection process can reach. The retained sample is what the pipeline selects from that frame. The frame may omit target units and include units outside the target; it may also contain duplicates or misclassified entries. Therefore even a random sample from the frame cannot justify claims about target situations that the frame never represented.

Sampling starts from the collection frame

Coverage can fail before sampling: the frame may omit target cases and admit cases outside the target population.

Target, frame, and retained sample

Partially overlapping boundaries expose undercoverage and erroneous inclusions before retained units are selected.

02.557.51002468Conceptual extent (conceptual units)Conceptual extent (conceptual units)Target populationCollection frameRetained sampleTarget populationCollection frameUnreachable target casesOut-of-target inclusionsRetained sample
  • 1. Target population
  • 2. Collection frame
  • 3. Retained sample
Read coordinates and regions as data

X: 010 conceptual units; Y: 08 conceptual units, increasing up. Equal scale on both axes.

Target population (polygon)

(0.8, 2); (1.2, 5.8); (2.5, 7); (5.8, 6.8); (7, 5); (6.6, 1.5); (4.8, 0.7); (2, 0.9)

Collection frame (polygon)

(3.2, 1.3); (3.5, 5.2); (5, 6.3); (8.7, 6); (9.4, 4.2); (8.7, 1.2); (7.1, 0.6); (4.8, 0.7)

Retained sample (points)

(4.2, 2.2); (5.1, 4.8); (5.8, 2.9); (6.5, 5.1); (7.2, 3.6); (8.1, 2.1)

Target population: (1.5, 6.2)

Collection frame: (8.9, 6.4)

Unreachable target cases: (1.4, 3.6)

Out-of-target inclusions: (8.9, 3.7)

Retained sample: (6.2, 2.4)

The retained marks are selected from the collection frame, not directly from the target population. Reweighting can adjust known selection probabilities but cannot create observations in the unreachable target-only region.

Selection serves different purposes

Probability sampling gives eligible units calculable, nonzero selection probabilities. Stratified sampling partitions the frame into mutually exclusive groups and samples within them, which can protect estimates or inspection for important subgroups. Deliberately oversampling rare failures can be useful for diagnosis or learning, but the resulting sample proportions no longer describe prevalence. Preserve the original group counts, selection rule, and inclusion probabilities when known; population estimates may require design weights.

A small coverage audit

ConditionTarget countReachable countRetained countInterpretation
Standard desktop flow700690140Broadly reachable; sampled down
Mobile with accessibility settings2008040Most target cases never entered the frame
Expired-session recovery1002040Rare reachable cases were deliberately oversampled
Internal test accounts06020Erroneous frame inclusions

The counts are invented to expose the relationships, not measured results. They show why plausible sample proportions are insufficient: the mobile gap began before sampling, while recovery cases are enriched by design. More desktop records cannot repair the missing mobile support, and reweighting cannot create observations for conditions with no collected examples. Coverage should also be checked across consequential combinations, not only one attribute at a time. Generated environment combinations can broaden coverage only after each combination is validated as a coherent task.

From summaries back to records

Profiling connects collection-level summaries to actual records. Start with structural checks—types, permitted values, key uniqueness, and referential integrity—but do not confuse conformance with truth. Add counts with explicit denominators, distributions, missingness patterns, and comparisons across relevant slices, meaning subsets that share a condition important to the intended use. Automatically inferred schemas and drift thresholds require review because they can reproduce defects or flag legitimate imbalance.

Three complementary inspections

  • Random inspectionSupports broad defect estimates only under its sampling and recognition assumptions. Even if the true defect fraction were 1%, a random sample of 100 would still have about a 37% chance of finding none.
  • Slice inspectionExamines conditions where aggregate summaries can hide concentrated omissions or errors.
  • Targeted inspectionFollows anomaly, disagreement, or change signals to suspicious records. It is useful for diagnosis but does not estimate population prevalence without accounting for selection.

A statistic is a pointer, not a verdict

SignalRecords to inspectPossible explanations
Missing-value rate risesRecords by source, time, and absence reasonCollector outage, newly optional field, privacy masking, or real nonresponse
Stable overall averageContributing slices and changed recordsOpposing subgroup changes cancel in aggregate
Rare extreme valuesOriginal records, units, and provenanceValid rare observation, unit mismatch, parser error, or duplicate event

An anomaly score should create a review queue, not an automatic deletion rule. The same extreme value can be a corrupt unit conversion or the only example of a consequential rare condition. Inspection returns to the source context because that is where the distinction can be justified.

Part III — Preserve meaning

Cleaning is semantic

Cleaning operations differ in what they assert. Parsing converts a representation into fields. Normalization chooses a common representation. Unit conversion changes a scale under a declared equivalence. Correction replaces a value judged wrong. Imputation supplies a value for missing or invalid data under assumptions. Filtering removes a record from a particular collection. Quarantine retains it outside accepted output for review or reprocessing. These are not interchangeable formatting conveniences.

Unknown is not zero

Suppose a source field says a refund amount is unknown. Converting a known “USD 12.00” string into a decimal amount plus currency preserves the observation when the parser is correct. Converting unknown into 0 asserts that no refund occurred, a claim the source never supplied. Quarantining the unresolved record preserves uncertainty while preventing a consumer that requires a numeric amount from silently treating it as accepted data.

One unknown value, three curation decisions

Example

Alternative derivations can preserve the observation, add an unsupported claim, or defer acceptance without changing the source record.

Three alternatives branch from the same refund record. A typed absence reason preserves what was observed; zero imputation adds a claim; quarantine retains the unresolved record outside numeric-only accepted output.
Read the diagram as text
  • Refund amount: unknown. The stable source establishes that no amount is known; it does not establish a zero refund.
  • Typed unknown. Store the applicable absence reason and retain the source link.
  • Asserted zero. A numeric zero invents the substantive claim that no refund occurred.
  • Quarantine. Retain the record for review outside output that requires an accepted numeric amount.
  • Refund amount: unknownTyped unknown: preserves absence reason.
  • Refund amount: unknownAsserted zero: adds unsupported value.
  • Refund amount: unknownQuarantine: defers acceptance.

Keep the raw input where handling rules permit, store the derived representation separately, and record the transformation, configuration, and affected fields. Compatibility normalization in Unicode illustrates why “standardization” is task-dependent: it can fold distinctions that matter to meaning. Likewise, an identity normalization such as treating West Germany and Germany as one entity changes historical counting semantics and must be an explicit policy rather than an invisible string replacement.

Filtering selects a population

Filters also change composition. Studies of C4’s blocklist found benign scientific, medical, identity-related, and dialect-associated text among rejected records. For creative image generation, a conventional aesthetic filter can remove intentionally blurred or low-resolution styles. Inspect rejected records and report retention by relevant slice rather than examining only what survived. For extraction from pages and preservation of evidence locations, see Locate supporting source material.

Duplicates depend on identity

Deduplication identifies and handles repeated content or observations under a declared identity rule. Byte-identical copies, copies made identical by normalization, overlapping passages, later revisions, records about the same entity, and repeated observations of the same process are different cases. Removing one may reduce accidental repetition; removing another may erase change, frequency, or independent evidence.

Similarity proposes; identity decides

PairDecisive distinctionTypical decision
Identical payload and event identityRetransmission of one eventRemove or make processing idempotent; retain frequency metadata if operationally useful
Same text after harmless formatting normalizationEquivalent document representation under the task’s ruleGroup and retain one representation plus provenance
Mostly identical text with a changed date, number, or negationLater revision may carry different evidenceRetain both versions and their validity relationship
Similar records from separate eventsRepeated observations are distinct evidenceRetain separately; group only for analysis if justified

From exact copies to candidates

Cryptographic content hashes efficiently generate candidates for byte-identical data; compare the content when identity matters. A normalized hash finds equality only after the chosen normalization. Neither match establishes that two records represent the same event. For near duplicates, split text into contiguous fragments called shingles and represent each document as a set. Their Jaccard resemblance is J(A,B)=AB/ABJ(A,B)=|A\cap B|/|A\cup B|. MinHash provides a compact estimate of this overlap, making candidate generation practical at scale. It does not verify semantic equivalence or shared event identity.

A safe pipeline generates candidates with methods appropriate to the comparison, verifies them under the identity rule, forms groups, and chooses representatives while retaining provenance and frequency information. At image scale, Krea reported using byte-oriented MD5 and perceptual pHash before more expensive embedding-based methods. These signals propose duplicate candidates; they do not establish event identity. Pairwise resemblance is not transitive: successive revisions may each resemble the next while the endpoints differ materially, so a connected cluster is not proof that every member is interchangeable.

A resemblance chain is not an identity decision

Example

Adjacent revisions can qualify as near-duplicate candidates even though the endpoints differ in a consequential field.

A–B and B–C exceed the example candidate threshold, so both pairs receive review. A and C do not qualify as a candidate pair, and the visible deadline change means the connected component cannot justify one interchangeable representative.
Read the diagram as text
  • Revision A. Cancellation deadline: June 1. Candidate resemblance to B: 0.91.
  • Revision B. Cancellation deadline: June 15. Candidate resemblance to A: 0.91; to C: 0.90.
  • Revision C. Cancellation deadline: July 1. Candidate resemblance to B: 0.90; endpoint resemblance to A: 0.74.
  • Identity-rule review. Inspect version, event, validity, and material changes before grouping or choosing representatives.
  • Revision ARevision B: candidate: 0.91 ≥ 0.85.
  • Revision BRevision C: candidate: 0.90 ≥ 0.85.
  • Revision AIdentity-rule review: review candidate set.
  • Revision BIdentity-rule review: review candidate set.
  • Revision CIdentity-rule review: review candidate set.

Separate related information

Training data is used to fit behavior. Development data informs choices such as features, prompts, thresholds, or configurations. A held-out test set assesses the frozen choice. Leakage occurs when information crosses a boundary the assessment intends to protect. Repeated inspection and tuning against a test set turns it into development data, regardless of its filename.

Match separation to the claim

Random row assignment is insufficient when rows share a person, source document, conversation, event, or revision family. Group related records before assignment if the intended claim concerns unseen groups. Use a temporal boundary when the intended use concerns future conditions, and include only features available at the decision time. A patient-disjoint split asks about unseen people; a later-period split asks about change over time; an external-site split asks about transport to another setting. These are different claims and can be combined.

Preprocessing can leak too. Fit statistics, imputation rules, feature selection, and learned normalization using training data alone, then apply the fitted transformation to development and test records. Even computing a normalization average over all rows exposes held-out information. Deterministic record validation against a predeclared rule is different from estimating a transformation from protected data.

Group before assigning dataset roles

Example

The protected boundary concerns shared information, so related records must be grouped before split assignment and preprocessing parameters must flow from training only.

Data edges carry records; control edges carry grouping, assignment, and fitted parameters. Held-out records never supply fitted preprocessing state.
Read the diagram as text
  • Versioned source records. Rows include stable IDs, entity or document-family keys, source versions, and event times.
  • Related-record groups. Exact copies, revisions, conversations, or shared entities are grouped under the intended independence rule.
  • Split assignment. Groups are assigned to training, development, or held-out test roles.
  • Training records. Used to fit model behavior and data-dependent preprocessing.
  • Development records. Used for selection without fitting preprocessing statistics.
  • Held-out records. Used after choices are frozen.
  • Fitted preprocessing state. Statistics and learned transformations estimated from training records only.
  • Versioned source recordsRelated-record groups: data: records.
  • Related-record groupsSplit assignment: control: keep groups intact.
  • Split assignmentTraining records: data: assigned groups.
  • Split assignmentDevelopment records: data: assigned groups.
  • Split assignmentHeld-out records: data: assigned groups.
  • Training recordsFitted preprocessing state: data: fit parameters.
  • Fitted preprocessing stateDevelopment records: control: apply only.
  • Fitted preprocessing stateHeld-out records: control: apply only.

Record stable IDs, grouping keys, source versions, split assignments, and the code or configuration that produced them. Then run exact and near-duplicate checks across the resulting boundaries. Historical coding-agent tasks illustrate a broader contamination problem: checking out an old commit did not isolate the task while future Git history and public issue discussions still exposed the solution. The protected boundary must include every equivalent information path, not merely one file or tool.

Part IV — Labels are claims

Specify the label

A label is an assigned target value or judgment; annotation is the process that produces it. A usable specification defines the unit being labeled, context annotators may inspect, allowed outputs, category meanings, decision rules, ambiguity handling, abstention, and whether several answers may be valid. A familiar word such as “fraud,” “resolved,” or “unsafe” is not a specification.

A label specification

QuestionRequired decision
What is the unit?For example, one login sequence rather than each individual attempt
What context is permitted?Whether later login success, multifactor authentication, and account history are visible
What does the label assert?Observed successful access, policy-defined notification need, or an analyst’s interpretation
What if evidence is incomplete?Abstain, mark unresolved, or request additional context rather than inventing a negative
When does the outcome mature?A deadline after which absence of an observed event can support the defined negative

In a password-spray example, many failed attempts and an eventual successful login begin with similar evidence but may receive different policy labels after the outcome is known. The additional feature resolves a specific ambiguity; it does not make every unsuccessful attempt harmless under every security policy. Pilot instructions on a small, varied batch, inspect disputes, and revise rules before scaling annotation.

Convenient targets can answer the wrong question

Observed outcomes, interpretations, and proxies must remain distinct. A ticket’s closed status records a workflow transition, not necessarily customer-confirmed resolution. A healthcare allocation model can accurately predict spending while spending remains a biased proxy for health need. Likewise, absence from a curated positive database is not a negative label: the unlabeled pool can contain undiscovered positives and true negatives. For coordinate transforms and spatial targets, see Preserving annotation meaning.

Disagreement is diagnostic

Independent annotation measures how consistently people apply a specification without seeing one another’s decisions. It does not create an infallible truth standard. Annotators can share the same misunderstanding, and subjective tasks can contain stable differences in perspective. Preserve individual judgments where feasible so aggregation does not destroy the evidence needed to diagnose disagreement.

Why 90% can mean little

Raw agreement is sensitive to category prevalence. If two independent random labelers each choose one category 95% of the time, their expected agreement is 0.952+0.052=0.9050.95^2+0.05^2=0.905, or 90.5%, despite having no item-specific ability. Chance-corrected measures adjust using assumptions about category frequencies and annotator behavior; they do not supply a universal acceptance threshold or validate the category definitions.

Resolve the cause, not only the vote

PatternLikely investigationPossible response
One annotator repeatedly violates a clear ruleTraining and error reviewCorrect affected labels and retrain the annotator
Disagreement concentrates in one categoryDefinition and boundary examplesRevise guidance; reconsider earlier batches
Decisions change when context is revealedContext availabilityExpose required evidence or allow abstention
Consistent perspectives remain after clarificationTask subjectivityRetain distributions or multiple labels where the use permits

Adjudication is an explicit process for resolving disputed cases into a reference annotation when the task requires one. It should record the decision and rationale, not erase the underlying disagreement. The reference remains fallible: automated candidate detection followed by human review of ImageNet labels found both majority-supported replacements and valid unusual examples among automated false alarms. Corrections should update affected records, examples, and instructions.

Automate without surrendering review

Weak supervision uses cheaper, imperfect sources such as rules, knowledge bases, or classifiers. In Snorkel’s formulation, a labeling function can emit a label or abstain, and overlapping, conflicting outputs are combined into probabilistic labels. Dependencies matter: two rules derived from the same keyword list are not two independent confirmations. A small labeled development set and a blind held-out test set remain part of the documented workflow.

One record, several sources

SourceOutputDependency or limitation
Rule A: keyword listPositiveShares the list with Rule B
Rule B: derived regexPositiveCorrelated with Rule A; not independent support
External databaseAbstainNo matching entry; absence is not negative
Model suggestionPositiveConfidence does not establish correctness
Independent reviewed judgmentUnresolvedRequired context is missing

Suggestions alter reviewer behavior

Model-assisted annotation can save work, but the interface changes the measurement process. In a Czech dependency-annotation study, annotation from scratch took almost 1.7 times as long as correcting strong parser suggestions, with broadly similar accuracy against adjudicated references in that task. Other experiments show that added effort for rejecting a suggestion can increase acceptance of incorrect suggestions. Assistance therefore needs independently assessed quality, not only throughput or reviewer agreement.

A Duolingo study inserted fabricated cheating alerts into previously certified exam sessions. Under the original guidance, reviewers rejected only half of those false suggestions; after guidance emphasized corroborating video evidence, rejection rose to 71% in a later study with different sessions. The result shows both the risk of automation bias and the value of testing whether reviewers resist known-bad suggestions. It does not isolate the guideline change as the sole cause.

Selection has blind spots

Active learning selects examples expected to improve a learner if labeled. Uncertainty sampling was studied for text classification in 1994, but uncertainty alone can miss confidently wrong regions: a 2008 hierarchical-sampling example shows a small cluster omitted by the initial sample while subsequent queries remain near the current decision boundary. Combine targeted review with random spot checks and coverage-based inspection. Agreement, confidence, and selection priority are signals for allocating review—not substitutes for correctness.

Part V — Release and maintain evidence

A release is a dependency graph

Data lineage connects source entities, transformation activities, and derived artifacts. Provenance answers where a record came from; lineage additionally shows what used it and what it generated. A reproducible dataset release needs more than a filename and script: it needs an immutable release identity, stable record identifiers, source versions or snapshots where permitted, content fingerprints, a membership manifest, processing code and configuration, annotation-guideline versions, grouping keys, and split assignments.

Recipe and state

A manifest records membership explicitly. Apache Iceberg, for example, represents a table state as a snapshot whose manifest list identifies immutable manifests and their files; readers retain the selected snapshot until refresh. DVC separates a declared pipeline recipe from recorded state such as commands, dependencies, outputs, hashes, and parameters. These mechanisms illustrate two complementary facts: what should run and what content actually participated in a particular result.

Rerunning the same query against a changing source is not reproduction. The source may add, remove, or revise records while the query text stays unchanged. Record the resolved source state and selection result. If retention rules forbid preserving raw material, retain the permissible identifiers, fingerprints, transformation records, and handling metadata—but do not claim those records can reconstruct unavailable content.

Lineage makes correction selective. If a source revision changes one record, trace it through cleaned derivatives, duplicate groups, annotations, split membership, released datasets, and downstream artifacts. Entity merges must preserve both source sets; a fact invalidated by new evidence should retain the evidence responsible for the change. Documentation such as a datasheet records purpose, composition, processing, intended uses, limitations, distribution, and maintenance so consumers can interpret the graph rather than merely reproduce its bytes.

A correction propagates through recorded dependencies

Example

Versioned lineage identifies the artifacts that require refresh while leaving unrelated artifacts untouched.

Each node is an immutable entity version or activity output. Derivation edges show why corrected source version S2 creates release R2 and invalidates only downstream artifacts that depended on S1.
Read the diagram as text
  • Source record S1. The original version with stable source identity and content fingerprint.
  • Cleaned artifact C1. Derived under recorded code and configuration.
  • Annotation A1. Produced under guideline version G1.
  • Release R1 manifest. Records membership, grouping, split assignment, and dependencies.
  • Dependent index I1. Built from release R1 and requires refresh after the correction.
  • Unrelated artifact U1. Has no dependency on source S1 and remains unchanged.
  • Corrected source S2. A new source version; S1 remains part of historical lineage where retention permits.
  • Release R2 manifest. Contains corrected derived membership and supersedes R1 for current permitted use.
  • Source record S1Cleaned artifact C1: derived by cleaning.
  • Cleaned artifact C1Annotation A1: annotated under G1.
  • Annotation A1Release R1 manifest: included by manifest.
  • Release R1 manifestDependent index I1: data dependency.
  • Corrected source S2Release R2 manifest: corrected derivation.
  • Release R1 manifestRelease R2 manifest: superseded by.
  • Release R2 manifestDependent index I1: requires refresh.

Data checks are not system success

Dataset acceptance and system usefulness are different claims. A release can pass schema, provenance, permission, coverage, separation, and label-review checks yet fail to improve a model or application. Conversely, an apparent system gain can arise from leakage, a changed model, more compute, or a different evaluation population rather than the curation change.

Two evidence contracts

ClaimEvidence requiredStill unresolved
Dataset meets its release requirementsManifest, validation results, coverage report, overlap checks, label audit, and handling reviewWhether a system using it performs better
A filter agrees with its rubricIndependent labels and a held-out confusion analysisWhether selected data improves downstream tasks
Dataset version B improves the intended systemComparable system conditions and independent reserved examples across relevant slicesTransfer to untested conditions and future drift

Controlled comparison

DataComp-LM addressed attribution by fixing a scale-specific training recipe, varying filters or mixtures, and measuring downstream models. FineWeb-Edu likewise separated filter agreement with model-generated educational labels from the later question of whether retained text improved tested capabilities; the chosen threshold also changed topic composition. A filter’s score is not an intrinsic property of text, and its preferred threshold is conditional on the task, rubric, corpus, training setup, and evaluation.

Preserve the exact dataset identity, change description, system configuration, and reserved examples used in the comparison. The Evals and Benchmarks chapter owns metrics, uncertainty, experimental design, contamination analysis, and release decisions. Curation’s responsibility is to make the data intervention identifiable and independently testable.

Maintain fitness through change

Maintenance begins by classifying the change. A source outage changes availability. A schema revision changes representation. A corrected record changes content. A withdrawal changes permitted membership. A shifting population changes composition. A revised category changes label meaning. These events require different responses. Drift simply means observed data properties changed; it is a signal to investigate, not proof of degradation.

Compare releases explicitly

  • MembershipAdditions and removals, with reasons and source versions.
  • ContentChanged records and fields, including before/after lineage where permitted.
  • CoverageCounts and proportions by important source, condition, and slice.
  • LabelsCorrections, taxonomy changes, guideline version, and adjudication rationale.
  • DependenciesDownstream datasets, indexes, evaluations, and models requiring refresh or review.

Detection is not propagation

Change feeds can support incremental maintenance by exposing inserts, deletes, and before/after updates with commit versions. They are not permanent history: retained versions can expire, and starting from an unavailable version can fail. Archive or checkpoint permissible state according to the release contract, and verify that downstream consumers actually applied the change rather than assuming event publication equals completion.

Reproducibility does not override current permission. The Stack’s removal process recorded requests and code pointers to prevent reinclusion, and required downloaders to use the most recent allowed version. An older reproducible release can therefore be an impermissible rollback target. Removing a row also does not remove its influence from an already trained model; identify affected model artifacts and hand remediation to the appropriate lifecycle owner.

Close the loop carefully

Assign an owner for source health, corrections, release decisions, and consumer notification. Prioritize new collection, repair, relabeling, or retirement by expected task impact and effort. Treat production feedback as another selected source: interfaces shape which users respond and which decisions are logged. Rubber-stamped model approvals can become misleading labels, so validate feedback against independent outcomes where possible. Maintenance preserves fitness only when it reconnects changed data to the original use contract.

Open questions

  1. How can coverage be measured when the target population is only partially observable? Practical frames omit people, events, and languages before sampling begins. Progress would require defensible proxies for missing support, explicit uncertainty about unreachable groups, and validation that collection interventions actually reach them.

  2. How should curators preserve legitimate disagreement without making downstream interfaces unusably ambiguous? Majority labels erase perspectives, while distributions or multiple references complicate training and evaluation. Progress would connect task subjectivity, annotator context, and decision costs to an explicit representation of uncertainty.

  3. How can automated curation discover confidently shared blind spots? Active learning and model-assisted review often prioritize uncertainty or disagreement, but correlated systems may confidently repeat one omission. Progress would combine independence-aware label sources, random and coverage-based audits, and outcome evidence that reveals errors outside the current model’s boundary.

  4. What is the right correction contract for derived datasets and trained models? Lineage can identify affected records and artifacts, but source deletion does not generally remove learned influence, and retention rules can forbid rollback. Progress would couple machine-readable dependencies with verified consumer updates, permitted historical state, and scoped remediation evidence.

  5. How should dataset fitness be maintained when intended use changes faster than labels mature? Operational and safety outcomes can arrive late, while input drift and source failures are observable immediately. Progress would keep pending outcomes explicitly unresolved, separate early operational signals from outcome evidence, and define review triggers without silently treating missing labels as success.

Follow the curated reading path through the speakers and demonstrations behind this entry.

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The rest of the library, beyond the curated path. Cited talks support this entry; reviewed transcripts were processed in full. Metadata candidates have not been reviewed as sources or verified as topic members.

21 matching talks

Every catalogued talk on this subject: Data and model adaptation

TalkSpeakerEventYear
Sandipan BhaumikAI Engineer Europe 20262026
Yuval Belfer, Niv GranotAI Engineer World's Fair 20252025
Jerry LiuAI Engineer World's Fair 20252025
Varsha ShahAI Engineer World's Fair 20262026
Diane LinAI Engineer World's Fair 20262026
Anant ShankhdharAI Engineer World's Fair 20262026
Kobie CrawfordAI Engineer Europe 20262026
Nathaniel Whittemore (NLW)AI Engineer Code 20252025
Vinesh GudlaAI Engineer World's Fair 20252025
Nathan SoboAI Engineer World's Fair 20252025
Louis-François Bouchard, Paul Iusztin, Samridhi VaidAI Engineer Europe 20262026
Ibragim BadertdinovAI Engineer Europe 20262026
Vincent KocAI Engineer Europe 20262026
Muktesh MishraAI Engineer World's Fair 20252025
Calvin Qi, Chang SheAI Engineer World's Fair 20252025
Mohak SharmaAI Engineer Summit 20252025
Maxime LabonneAI Engineer World's Fair 20242024
Mahmoud MabroukAI Engineer Europe 20262026
Raj NavakotiAI Engineer Europe 20262026
Brandon WaselnukAI Engineer Europe 20262026
Rafael LeviAI Engineer Europe 20262026

References

Coverage and source review
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26 processed in full · 5 in the curated path
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Automated review checks source support; it is not publication approval.

A synthesis of selected conference talks and technical references. Citations link to the source material; they do not imply that every talk on this subject is included.

  1. The Government Data Quality Framework

    Data quality means suitability for an intended purpose, with requirements determined by users and their needs. The framework distinguishes completeness, uniqueness, consistency, timeliness, validity and accuracy; complete or correctly formatted records can still contain incorrect values. Different uses can require different priorities and tradeoffs. Quality assessment belongs throughout collection, processing, sharing and maintenance, with documented limitations, accountable owners and communication of changes. The framework explicitly distinguishes input-data quality from assurance of analytical outputs.

  2. Datasheets for Datasets

    Datasheets proposes documenting purpose, composition, collection, preprocessing, uses, distribution and maintenance. Questions distinguish observed, reported and inferred data; request descriptions of labels, sampling strategies and representativeness; and ask what cleaning occurred and whether original data and processing software remain available. Suitability and use restrictions are documented separately. Maintenance questions identify owners, correction mechanisms and how additions, deletions and labeling updates reach consumers. Its word-order example shows why a transformation suitable for one task can make data unsuitable for another.

  3. Cross-validation and held-out evaluation

    Testing on data used to fit or repeatedly tune a system can overestimate generalization. The documentation separates training, validation for selection, and an untouched final test set; cross-validation does not eliminate the need for final held-out evaluation. Applied to model judges, tune rubrics and examples on calibration data, freeze the judge, then measure agreement with independent human labels on unseen examples. Applied to context policies, select retrieval and compression settings on development tasks and evaluate the selected policy on held-out tasks. Repeatedly changing settings after seeing test results converts that test set into development data.

  4. Training Krea 2 - What matters in generative model training.

    Curate against the intended aesthetic coverage rather than relying exclusively on conventional aesthetic or image-quality scores.

  5. Krea 2 Technical Report

    Krea's team describes curation for creative exploration, where stylistic diversity matters and blur can be an intentional artistic choice. Its filtering therefore considers image-caption alignment and representability at the training resolution rather than simply retaining the highest aesthetic scores. The team also reports that cluster-based sampling can discard individual named entities within broad visual categories. It checks captions against a Wikipedia-derived concept list, prioritizes rare concepts, and repeats the check after sampling to identify concepts lost during selection.

  6. PROV-DM: The PROV Data Model

    Provenance records the entities, activities and responsible agents involved in producing or delivering information. Entities include files and document versions; activities use and generate entities; derivation connects an output to an earlier entity through transformation, update or construction. These relationships provide a concrete representation for source-to-derived-data lineage. PROV distinguishes a particular document version from a resource identifying its changing latest version and warns that provenance descriptions must remain valid as resource state changes.

  7. Deduplicating Training Data Makes Language Models Better

    Lee and colleagues compared exact repeated-substring removal with approximate document deduplication. Exact-substring removal eliminated 7.18% of C4 training tokens; near-duplicate matching found training counterparts for 4.60% of C4 validation examples. In their 1.5-billion-parameter models after two epochs, the fraction of generated tokens belonging to copied training sequences fell from 1.571% on original C4 to 0.168% after exact-substring deduplication. The generation test used 100,000 unprompted sequences, each up to 512 tokens, and counted matches of at least 50 tokens.

  8. Beyond Accuracy: What Data Quality Means to Data Consumers

    Wang and Strong's Spring 1996 paper investigated data quality through surveys of data consumers and subsequent sorting studies. It organized quality into intrinsic, contextual, representational and accessibility categories. The motivation was that improvement efforts focused too narrowly on accuracy, overlooking whether people could interpret, access and use data for their tasks. This establishes a pre-AI foundation for purpose-dependent curation.

  9. DataComp-LM: In Search of the Next Generation of Training Sets for Language Models

    DataComp-LM addresses a comparison problem: changing data, model architecture and compute simultaneously makes improvements difficult to attribute to curation. Its workflow fixes a scale-specific training recipe, varies filtering or data mixtures, then assesses resulting models on downstream tasks. In the reported experiments, classifier-based filtering was effective, but the choice of positive and negative examples substantially affected filter usefulness. This makes dataset selection an empirical engineering decision rather than treating a filter's quality score as an intrinsic property of text.

  10. On the Two Different Aspects of the Representative Method

    Neyman's 1934 paper contrasted stratified random sampling with purposive selection intended to reproduce known population characteristics. He showed through mathematical analysis and constructed populations that matching selected control averages need not preserve other quantities or distributions. His argument favored sampling procedures whose uncertainty could be assessed over repeated samples, rather than judging representativeness from a sample's apparent resemblance alone. Time and resource constraints motivated studying samples instead of entire populations.

  11. A Theory for Record Linkage

    Ivan Fellegi and Alan Sunter, at Canada's Dominion Bureau of Statistics, formalized linkage between records representing the same person, object, or event. Their December 1969 paper addressed maintaining administrative files and combining information across collections. Recording errors mean one entity can produce different records, while different entities can produce identical recorded attributes. Their decision rule distinguishes links, non-links, and unresolved pairs requiring further review. Under its probability model, it minimizes unresolved decisions at specified false-link and missed-link error levels.

  12. On the Resemblance and Containment of Documents

    Broder's work at Digital Systems Research Center addressed near-identical web documents when comparing every full document pair was impractical. It used compact document sketches and reported application to an AltaVista crawl. Beyond the shingling mechanism, the paper identifies two useful limitations: larger shingles increase sensitivity to small edits, and strong resemblance is not transitive. Successive revisions can each resemble their predecessor while distant revisions differ substantially. Pairwise similarity therefore does not make every member of a connected duplicate cluster interchangeable.

  13. Datasheets for Datasets: March 2018 Working Draft

    The March 23, 2018 working draft proposed dataset datasheets by analogy with electronic-component documentation, aiming to communicate construction, appropriate uses and limitations between creators and users.

  14. Apache Beam glossary

    Event time describes when an event occurred, according to its timestamp; processing time describes when a pipeline processes it. Events need not arrive in event-time order. A user interaction can therefore have an occurrence time different from the time its record is handled.

  15. HL7 Terminology: DataAbsentReason

    HL7 distinguishes a value that is unknown, temporarily unknown, not asked, declined, masked for security or privacy reasons, inapplicable, or unsupported by the source system. These codes explain why expected content is absent. They provide a concrete example of preserving missingness reasons instead of collapsing different collection circumstances into one blank value.

  16. ODRL Information Model 2.2

    ODRL represents permissions, prohibitions and duties associated with use of an asset. Rules identify actions, involved parties and applicable constraints. Machine-readable policies can be linked to the content they describe so consumers can retrieve its terms of use and reuse.

  17. Scaling Enterprise-Grade RAG Systems: Lessons from the Legal Frontier

    Storage segregation and document retention must be configurable for the customer and use case.

  18. Statistics Canada Quality Guidelines: Coverage and frames

    The target population comprises the units about which information is wanted. Practical exclusions can narrow this to a survey population. A sampling frame identifies and provides access to units; omissions, duplicates, erroneous inclusions and misclassifications create coverage errors. Probability sampling from a restricted survey population does not automatically justify claims about the broader target population. The guidance recommends documenting these differences and periodically checking frame coverage against other sources.

  19. Statistics Canada: Survey Methods and Practices

    Probability sampling uses random selection with calculable, nonzero inclusion probabilities. Stratified sampling partitions a population into mutually exclusive groups and samples within them, supporting subgroup estimates. Judgment sampling deliberately selects cases and can help exploratory work, but its unknown selection probabilities limit population inference. Design weights are inverses of inclusion probabilities. Disproportionate subgroup sampling therefore changes sample proportions and requires the sampling design to be reflected in population estimates.

  20. Computer Use at the Edge of the Statistical Precipice

    Vary task data, appearance, and initial state across runs, while checking that every generated combination remains valid.

  21. TensorFlow Data Validation: Checking and analyzing your data

    TFDV compares dataset statistics with expectations such as types and permitted categorical values, supports checks before and after transformations, and compares training with serving data or consecutive data spans. Automatically inferred schemas capture basic properties and require user review. Distribution visualizations expose missing values and suspicious patterns, but an imbalanced feature can occur naturally. Drift thresholds require domain knowledge and experimentation.

  22. NIST: Choosing a Sampling Plan with a Given OC Curve

    NIST models defect counts in a random sample using a binomial approximation when the collection is much larger than the sample. Substituting zero defects into its formula gives P(no defects observed)=(1-p)^n, where p is the collection's defect fraction and n is the sample size. Constructed illustration: with a 1% defect fraction, inspecting 100 randomly selected records still has about a 37% chance of finding none. A clean audit sample therefore does not establish a defect-free collection.

  23. Failing Loudly: An Empirical Study of Methods for Detecting Dataset Shift

    The paper separates detecting an input-distribution change, identifying examples characteristic of that change, and determining whether prediction quality worsened. Distribution changes can be benign. Conversely, compressing inputs into monitored representations can hide changes because distinct inputs may map to the same representation. A classifier distinguishing reference from current data can surface characteristic records for inspection, but directly assessing prediction error on current data requires labels.

  24. Statistics Canada Quality Guidelines: Imputation

    Imputation assigns replacement values to missing, invalid or inconsistent data after applicable follow-up and correction. Statistics Canada recommends reproducible methods and audit trails, retaining original and imputed values, and recording which values changed, the method and any donor records. Treating imputed values as observations can mislead. Aggregate stability can conceal opposing changes in different subgroups, so assessment should examine affected domains and relationships as well as overall quantities.

  25. Databricks: Expectation Recommendations and Advanced Patterns

    The documented quarantine pattern marks records violating explicit rules and exposes separate valid and invalid views, retaining failed records for separate processing. Its taxi example tests whether pickup and drop-off ZIP fields are present. The documentation also distinguishes validation from orchestration: a separate validation table does not automatically prevent downstream tables from updating. Enforcing a release gate requires an execution dependency that actually waits for validation success.

  26. Unicode Standard Annex #15: Unicode Normalization Forms

    Unicode distinguishes canonical equivalence from weaker compatibility equivalence. NFC preserves distinctions between compatibility-equivalent characters, whereas NFKC and NFKD fold those distinctions. Compatibility normalization can remove formatting or distinctions important to meaning and should not be applied indiscriminately. Normalizing representation is therefore a task-dependent transformation, not automatically a harmless repair.

  27. RAG Evaluation Is Broken! Here's Why (And How to Fix It)

    Entity identity and attribute cardinality must be resolved consistently during ingestion and query interpretation.

  28. Documenting Large Webtext Corpora: A Case Study on the Colossal Clean Crawled Corpus

    The authors examined documents excluded by C4's word blocklist, finding scientific, medical and other non-offensive content among removals. Identity-mention analysis and manual inspection showed exclusion of benign material discussing sexual orientations. A dialect-model analysis found disproportionate removal of text assigned African American English and Hispanic-aligned English categories. Inspecting rejected records therefore revealed composition effects that examining only the retained corpus would miss.

  29. Introduction to Information Retrieval: Near-duplicates and shingling

    A k-shingle is a contiguous sequence of k terms; each document becomes a set of such sequences. Jaccard similarity is |A intersection B|/|A union B|. A threshold identifies substantial textual overlap. MinHash estimates this similarity because, under a random permutation, the probability that two sets share the minimum element equals their Jaccard similarity. Exact fingerprints and approximate overlap serve different purposes. Application inference: keep document identity, source location, revision identifier, content hash, validity and provenance separately from duplicate-cluster membership. A small change to a date, number or negation can be material despite high overlap.

  30. CloudEvents Specification v1.0.2

    CloudEvents requires producers to make the combination of source and id unique for each distinct event. A retransmitted duplicate may retain its id, and consumers may treat matching source–id pairs as duplicates. This supplies an explicit event identity rule independent of whether two payloads contain similar text.

  31. Training Krea 2 - What matters in generative model training.

    Apply inexpensive hash-based deduplication before more costly embedding-based duplicate detection.

  32. TRIPOD+AI expanded checklist: timing, labels, and evaluation separation

    Specify the intended decision point t0, eligible population, predictor definitions and measurement times, and outcome assessment procedure. For prognosis, define the horizon h, such as an event within 28 days after t0. For diagnosis, identify the reference standard used to determine condition status. Predictors should be measured before or when the model is intended to run; assessment and blinding procedures must avoid outcome leakage. Report participant overlap, including repeated records, across training, tuning, and evaluation. Engineering interpretation: patient-disjoint evaluation asks about unseen people; a later-period evaluation asks about performance as time and practice change; evaluation at another institution asks about transport across settings. These dimensions can be combined, and their dates, populations, and differences must be explicit.

  33. scikit-learn: Common pitfalls and recommended practices

    Preprocessing learned from data must be fitted using training data alone and then applied to held-out data. Even an average used for normalization leaks information if computed over the test subset. The documentation applies this warning to feature selection, scaling, imputation and PCA, and demonstrates misleading above-chance performance on random labels when feature selection sees test data. Pipelines help fit transformations on the correct subset during cross-validation.

  34. SWE-rebench: Lessons from Evaluating Coding Agents on Real Software Engineering Tasks — Ibragim Badertdinov, Nebius

    An agent can recover the solution through retained future Git history or public repository access, and disabling one retrieval tool does not close equivalent paths.

  35. Analyzing Dataset Annotation Quality Management in the Wild

    The paper recommends iterative annotation batches: pilot the scheme and instructions, inspect quality, then correct labels, train annotators or revise guidelines. A scheme defines available labels; guidelines explain when to apply them. Multiple judgments support agreement checks and adjudication, meaning resolution into a final annotation. Expert inspection and error-rate audits remain distinct from agreement measurement. Major guideline changes can require reannotation of earlier batches. Retaining individual annotations supports reproducibility and preserves information lost during aggregation.

  36. Google: Supervised learning foundations

    Features are input values x; a label y is the target recorded for an example. Parameters θ are learned numbers defining a model fθ. Training repeatedly compares predictions with labels using a loss and adjusts these numbers to improve agreement. Inference evaluates the trained function on a new input without needing its label. Generalization means performing well on examples outside training; evaluation therefore compares predictions against withheld labels. Programmer-oriented illustration: training fits w and b in f(x)=wx+b from examples, whereas an authored rule such as if x>c executes a programmer-specified condition. Both execute code at inference, but the origin of their decision behavior differs.

  37. Stripe card-dispute timing and lifecycle

    A dispute becomes observable to a merchant when Stripe notifies it through configured channels or the API, after the account owner contests a payment. Cardholders usually have 120 days to initiate a dispute, with exceptions; future-service windows may start at the service date. Early fraud warnings and inquiries can precede formal disputes, but warnings can also arrive afterward. A case can await evidence or issuer review before its status becomes won or lost; rare late wins can revise a loss. An inquiry closed without escalation is not an explicit issuer win. Label-design implication: preserve payment time, observation time, reason and evolving status. At a chosen cutoff, an unresolved case remains unresolved, and no recorded dispute means only that none has been observed by then, not confirmed non-fraud.

  38. Why Your Agent Disagrees With Itself (And What To Do About It)

    The password-spray example distinguishes failed attempts from successful access and combines that evidence with the customer's notification policy.

  39. Right censoring and unresolved event outcomes

    Let T be event time and C the end of observation. A right-censored record stores U=min(T,C) and an indicator delta showing whether the event was observed. When delta=0, the record establishes only that the subject remained event-free through C; the later outcome is unknown. Survival models use this partial information rather than treating C as an event time. S(t)=P(T>t) describes survival beyond t. Financial application: for a default-within-H label, an account observed without default only until C<H is unresolved, not a negative example. A negative requires sufficient event-free follow-up through H.

  40. Zendesk: What is the difference between a solved ticket and a closed ticket?

    Agents can mark a ticket solved after resolving the issue or completing work. Closure is performed through automation or triggers. A reply can reopen a solved ticket, but a reply to a closed ticket creates a follow-up while the original remains closed. Thus, for this documented workflow, a closed status records a workflow transition and does not by itself establish customer-confirmed resolution.

  41. Obermeyer et al.: Healthcare cost as a biased proxy for need

    The studied algorithm ranked patients for extra care using predicted healthcare spending as a proxy for health need. Black patients were sicker than White patients at the same score. The authors linked this mismatch to lower spending on Black patients at comparable illness burden, reflecting unequal access and utilization. Predicting the chosen cost label could therefore work while allocation by that score underserved patients with greater need. Their estimated correction increased the Black share selected for additional help from 17.7% to 46.5%. The mechanism is target mismatch: accurate prediction of resource consumption does not establish accurate measurement of need.

  42. Learning Classifiers from Only Positive and Unlabeled Data

    Charles Elkan and Keith Noto distinguish an example's actual class from whether someone has labeled it. Their biological-database example contains known qualifying proteins but no explicit collection of nonqualifying proteins. Records absent from that specialized database can include both undiscovered positives and negatives. Consequently, absence from the curated collection cannot simply become a negative label. Their proposed learning methods explicitly model the relationship between class membership and label availability.

  43. Inter-Coder Agreement for Computational Linguistics

    Inter-annotator agreement measures consistency of judgments on the same items, not their independent correctness: annotators can share a mistaken interpretation. The paper's mathematical examples show why category prevalence matters. If two independent random labelers each assign one category 95% of the time, their expected agreement is 90.5%, despite having no item-specific judgment ability. Chance-corrected measures use different assumptions about category frequencies and annotator behavior, so their values require interpretation alongside the labeling task and distributions.

  44. Dealing with Disagreements: Looking Beyond the Majority Vote in Subjective Annotations

    For subjective annotation tasks, majority aggregation can hide systematic differences between annotators and discard internally consistent perspectives. The paper preserves annotator-specific labels and evaluates methods across seven subjective tasks. Its findings support investigating disagreement rather than automatically treating minority judgments as random errors. The authors recommend retaining individual annotations where feasible, with appropriate consent and anonymization.

  45. Pervasive Label Errors in Test Sets Destabilize Machine Learning Benchmarks

    Northcutt, Athalye, and Mueller used automated error detection followed by human review rather than automatically replacing suspicious labels. For ImageNet's 50,000-example validation set, their method flagged 5,440 candidates. Five workers reviewed each candidate: 2,524 retained support for the original label, and 1,428 received a majority-supported replacement. Other cases involved multiple plausible labels, neither offered label, or unresolved disagreement. Their inspection also found valid unusual viewpoints and cropped objects among automated false alarms.

  46. Snorkel: Rapid Training Data Creation with Weak Supervision

    Weak supervision uses cheaper, imperfect label sources such as rules, external knowledge bases and weak classifiers. Snorkel's 2017 system lets domain experts express these sources as labeling functions that return a label or abstain. It combines their overlapping and conflicting outputs into probabilistic labels. Modeling correlations matters because similar heuristics can otherwise be counted as independent support. Although its label-combination step uses unlabeled training examples, the paper explicitly assumes a small labeled development set and a blind, held-out labeled test set.

  47. Quality and Efficiency of Manual Annotation: Pre-annotation Bias

    Marie Mikulová and colleagues compared manual correction of parser-generated annotations with annotation from scratch for Czech dependency syntax: identifying which word each word depends on and the relationship type. Four annotators worked across eight setups without annotating the same material twice. Annotation from scratch took almost 1.7 times as long on average. Accuracy against adjudicated reference annotations remained broadly similar, while pre-annotation increased agreement. This demonstrates a setting where automated suggestions reduced work without the observed quality loss that concern about suggestion bias might predict.

  48. Bias in the Loop: How Humans Evaluate AI-Generated Suggestions

    Jacob Beck and colleagues randomized annotation-workflow conditions for 2,784 participants checking emissions values against corporate-report tables. Suggestions were manually manipulated and presented as AI outputs. Requiring reviewers to enter a replacement value when rejecting a suggestion reduced corrections: reviewers accepted more incorrect suggestions but also rejected fewer correct ones. Aggregate accuracy was slightly higher despite increased acceptance of errors. The experiment therefore exposes a consequential distinction between overall accuracy and the particular mistakes a curation workflow permits.

  49. When Machines Mislead: Human Review of Erroneous AI Cheating Signals

    Duolingo researchers William Belzak, Chenhao Niu, and Angel Ortmann Lee inserted fabricated copy-typing alerts into previously certified exam sessions. Each of two studies sampled 170 sessions. Model-estimated rejection of fabricated alerts increased from 50% under the original guidelines to 71% after guidelines emphasized corroborating video evidence. Thus human review rejected many false suggestions but also accepted some. Operational alerts were rejected more often after the revision, although their underlying correctness was not independently established.

  50. Build AI Systems for Discernment, Not Approval - Angel Ortmann Lee, Duolingo

    The When Machines Mislead case study inserted fake copy-typing alerts into legitimate historical exam sessions and found that skilled proctors accepted half of those alerts.

  51. A Sequential Algorithm for Training Text Classifiers

    David Lewis and William Gale at AT&T Bell Laboratories studied uncertainty sampling to reduce the labeling needed for text classification. Their loop trains a classifier, selects unlabeled examples whose categories are uncertain, obtains their labels, and retrains. In their 1994 newswire experiments, uncertainty selection generally reached useful classification performance with fewer labeled examples than random selection or selecting the most likely positives. This separates choosing informative examples for learning from choosing examples representative of population proportions.

  52. Hierarchical Sampling for Active Learning

    Sanjoy Dasgupta and Daniel Hsu's 2008 paper shows why uncertainty-driven labeling can overlook confidently misclassified regions. In its one-dimensional teaching example, an initial sample misses a small group; subsequent queries remain near the current decision boundary, so the overlooked group never corrects the learner's mistaken confidence. Their alternative uses hierarchical clusters and random sampling within selected regions, updating label statistics and refining the partition. It combines informative selection with explicit management of sampling bias.

  53. Why Your Agent Disagrees With Itself (And What To Do About It)

    Active learning selects potentially problematic examples for human clarification, then incorporates corrected labels or additional features into the next training cycle.

  54. Apache Iceberg Table Specification

    An Iceberg snapshot represents a table state at a particular time. Immutable manifest files list data or delete files with partition and tracking metadata; a manifest list identifies the manifests belonging to a snapshot. Membership is established through explicit metadata rather than simply reading everything currently present in a directory. Readers retain their selected snapshot until refreshing metadata.

  55. DVC: dvc.yaml Files

    DVC separates pipeline declarations in dvc.yaml from recorded pipeline state in dvc.lock. Lock entries include stage commands, dependencies, outputs, content hashes and parameter values. These records support detecting changed stages and identifying the data versions associated with pipeline outputs. A recipe and its recorded input/output state therefore provide complementary parts of reproducibility.

  56. Citation Needed: Provenance for LLM-Built Knowledge Graphs

    Lineage must survive graph mutation: entity merges retain both source sets, and invalidation records the new evidence responsible for the change.

  57. The FineWeb Datasets: Decanting the Web for the Finest Text Data at Scale

    Penedo and colleagues trained an educational-content filter using model-generated ratings focused on grade-school and middle-school knowledge. They compared filtering thresholds using 1.71-billion-parameter models trained on 28 billion tokens; threshold 3 provided the best average performance in those experiments. Filtering also changed topic composition: FineWeb-Edu increased representation of education and history while reducing business and entertainment. The filter's reported validation F1 measured agreement with Llama-generated annotations, whereas downstream model experiments assessed a different question: whether the selected text improved the tested capabilities.

  58. scikit-learn confusion_matrix

    A confusion matrix counts reference classes in rows and predicted classes in columns. With acceptable=1 and unacceptable=0, false acceptance is C[0,1] and false rejection is C[1,0]. Conditional rates are C[0,1]/(C[0,0]+C[0,1]) and C[1,0]/(C[1,0]+C[1,1]); a zero denominator leaves that rate undefined. Applied to judge validation, freeze the rubric and acceptance threshold, obtain independent reference labels, and compare judge decisions on held-out examples. Keep unresolved human disagreements and abstentions separately visible.

  59. FineWeb-Edu dataset card

    The dataset card reports that educational-score threshold 3 retained approximately 1.3 trillion tokens, while threshold 2 retained 5.4 trillion. These are retained corpus volumes, not quantities consumed in one training experiment. Its changelog distinguishes additions from repairs: version 1.3.0, dated January 31, 2025, corrected documents skipped during processing and added approximately 35 billion tokens across listed snapshots; other releases added newly collected snapshots. Earlier versions remain available through named branches.

  60. Databricks: Use Change Data Feed

    Change data feed exposes row-level inserts, deletes and updates between table versions. Update records distinguish values before and after modification, with commit versions and timestamps. Consumers can use these records to update downstream datasets incrementally. The feed is not a permanent history: changes become unavailable when their retained versions expire, and restarting from an unavailable version fails. A reproducible maintenance process therefore needs to account for both what changed and whether the required history remains accessible.

  61. BigCode: The Stack Datasets and Removal Process

    The Stack's release history records changes to included licenses and removal requests: version 1.1 excluded requests submitted by November 15, 2022, and version 1.2 excluded requests submitted by February 9, 2023. Its process retains validated removal requests and code pointers to prevent reinclusion. Downloaders must agree to use the most recent allowed version. The page also states that original code-license terms continue to apply and that record provenance supports attribution. Thus an older reproducible release is not automatically an allowable rollback target.

  62. Machine Unlearning

    Removing records from a stored dataset is distinct from removing their influence on an already trained model. The paper explains that successive training updates depend on earlier updates, so a record's contribution is not generally undone by deleting its original row. It formulates removal from learned models as a separate technical problem. For curators, this supports identifying affected model artifacts and handing off remediation rather than declaring downstream effects reversed after source deletion.

  63. Build AI Systems for Discernment, Not Approval - Angel Ortmann Lee, Duolingo

    The human-AI interaction loop is cyclical: interfaces that encourage rubber-stamping can turn model-influenced approvals into misleading evaluation and training labels.

  64. Build Your First Demand-Driven Context Base: Let AI Agents Tell You What They Need

    They provide maintenance signals, but the Q&A leaves semantic correctness and economical refresh at scale unresolved.

  65. Your Evals Are Meaningless (And Here’s How to Fix Them)

    Dataset drift, as used in the talk, includes inadequate coverage of messy, ambiguous, and combined real-user requests.

  66. Task Fidelity Scaling Laws — Kobie Crawford, Snorkel AI

    Snorkel describes shared rubrics and expert-provided ground truth as the basis for checking agreement among humans and between humans and LLM judges.

  67. Why Your Agent Disagrees With Itself (And What To Do About It)

    The speaker argues that unstable examples tend to occupy the decision boundary, or gray zone, where labels or available information are ambiguous.

  68. Judge the Judge: Building LLM Evaluators That Actually Work with GEPA — Mahmoud Mabrouk, Agenta AI

    Include the reason for each verdict, especially when the judge must learn a complex policy.

  69. Build Your Own Deep Research Agent + Technical Writer

    The demonstrated judge passed every simulated online trace despite labeled failures, showing that its small-split results did not establish reliable behavior on those scenarios.

  70. Weak supervision needs evaluation beyond supervisor agreement

    Oversight becomes difficult when an evaluator cannot reliably judge behavior available to a stronger model: matching its labels can reproduce its mistakes. The paper trains a weak model on ground-truth labels, obtains its predictions on held-out examples, and trains a stronger student on those weak labels. It compares ground-truth test performance with both the weak supervisor and a strong model trained directly on ground truth. Performance gap recovered is PGR=(student-weak)/(strong_ceiling-weak), requiring a nonzero denominator. PGR=0 means no improvement over the supervisor; PGR=1 matches the experimental ceiling. Independent correctness scores and agreement on supervisor-wrong examples distinguish useful generalization from imitation. Experiments show task-dependent generalization and overfitting to weak labels; an auxiliary confidence loss improves some NLP results.

  71. NIST AI RMF: Monitoring, incident response, and recovery

    NIST calls for ongoing risk tracking, user feedback, documented incident response and recovery, change management, and assigned authority to override or deactivate systems inconsistent with intended use. It explicitly considers tracking risks when suitable metrics are not yet available. Engineering application: define escalation owners and suspension criteria, preserve incident and version records, restore an evaluated safe operating mode, and evaluate changed behavior before resuming. When clinical labels arrive late, monitor input availability, operational failures, and reported incidents immediately, then calculate outcome metrics on cohorts whose follow-up has matured. Pending labels must remain unknown rather than being counted as negative outcomes or successful predictions.

  72. Training Krea 2 - What matters in generative model training.

    Match sample complexity to training resolution, then use curated mid-training and supervised fine-tuning data to shape the model toward downstream uses.

  73. Citation Needed: Provenance for LLM-Built Knowledge Graphs

    A synthesized fact can hide both its original wording and the authority of its actual source, so retain verbatim inputs and explicit links to derived artifacts.

  74. Citation Needed: Provenance for LLM-Built Knowledge Graphs

    Project ingestion metadata onto derived artifacts so retrieval can filter by source classification.

  75. Computer Use at the Edge of the Statistical Precipice

    Confidence intervals should account for both action stochasticity and environment variation while respecting the benchmark's structure.

  76. Data and Environment Curation for Post-training LLMs

    Treat curation as a sequence of experimentally tested choices, including source mixing, question filtering, teacher selection, answer filtering, and answer multiplicity.

  77. Data and Environment Curation for Post-training LLMs

    Sampling multiple answers per question reportedly helped both reasoning-model and agent-data curation.

  78. Data and Environment Curation for Post-training LLMs

    Answer filtering reportedly worked poorly in the reasoning-data work, while synthetic rewriting and task augmentation worked poorly in the agent-data work.