ADD NEW
    0
    ADD NEW
    G06 · TOPIC · evidence-classesGCRI dossier · service level R0
    GCRINexus RegistryEstablished
    Topic dossier · Nexus Registry

    Evidence classes

    Not all evidence carries the same weight. A peer-reviewed trial, an official statistic, a model output, a press statement and an owner's own declaration can all support the same sentence, yet each warrants a different degree of reliance. Evidence classes make that difference visible. This page sets out how records are classed by evidence type, how confidence is stated, how reliance limits are set, and why claims drift beyond what their evidence supports.

    Make an enquiry Back to Topics
    DossierG06 · topic
    1. 01In briefDefinition and scope
    2. 02The question4 mechanisms
    3. 03Key terms3
    4. 04FieldH3 field plate
    5. 05Indicators7
    6. 06PipelineRun graph
    7. 07Sources6
    8. 08Decision holders4
    9. 09Methods3

    GCRI · Established · service level R0

    01In brief

    The short answer.

    Evidence classes are labels that record what kind of evidence supports an assertion, such as a peer-reviewed study, an official statistic, a model output or an owner's declaration, so readers can judge how much to rely on it. Confidence statements need a stated basis, and claims tend to drift beyond what their class supports.

    02Geography

    People and hazards in World.

    For evidence classes, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery and land cover with true colour from NASA GIBS, framed on World; every other NASA layer, live feed and forecast waits in the layer list.

    The interactive map needs JavaScript; the layer list and sources are below.

    Layers 2

    People and hazards, for this page

    Latest available

    NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth

    Loading the latest NASA imagery.

    Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.

    For evidence classes, in GCRI's spatial-intelligence reading, the map opens on true-colour imagery and land cover with true colour from NASA GIBS, framed on World; every other NASA layer, live feed and forecast waits in the layer list.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.

    Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · Copernicus Sentinel-2 L2A · NASA HLS S30Sources and licences

    • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). CC BY 4.0
    • VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
    • © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). ODbL
    • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
    • Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
    • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
    • Observed (EO): Copernicus Sentinel-2 L2A (contains modified Copernicus Sentinel data 2026), Microsoft Planetary Computer
    • Observed (EO): NASA HLS S30 (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS).
    • Optional layers (35 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.

    Layers and dates

    • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
    • Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
    • Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
    • Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
    • Enhanced vegetation index, rolling 8 days: MODIS Terra EVI, NASA LANCE · 13 Oct 2026
    • Vegetation greenness (NDVI), rolling 8 days: MODIS Terra NDVI, NASA LANCE · 13 Oct 2026

    03Console

    Record ledger, in outline.

    The working screen behind this subject: its structure, terms and states. Names are placeholders and values illustrative.

    Record ledger

    Evidence classes · Registry · Ledger head 3142470

    • Records registered
      5701
    • Complete provenance, % of records
      92Normal
    • Open corrections
      10Watch
    • Rights holds
      4Info
    Integrity check passedGCRI · Nexus Registry

    Latest records

    NX-R-12221Programme statusv24472615Registered
    NX-P-88287Publicationv31324692Registered
    NX-E-72567Evidence recordv44410118Correction open
    NX-C-27773Participationv17438493Rights hold

    Version history

    1. v1NEWRegistered with sources
    2. v2FIXUnit corrected, reason recorded
    3. v3OPENCorrection requested
    Record ledger: the screen's structure, terms and states for Evidence classes.Placeholder names and illustrative values; a design, not a record or a live system.
    04The question

    Evidence classes: how the risk develops.

    Evidence type, reliance limits and confidence. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.

    Mechanism

    Class collapse

    When observed, modelled, reported and declared evidence share one field with no label, a reader cannot tell a measurement from a projection or a self-assessment. The weakest source then borrows the authority of the strongest.

    Mechanism

    Claim creep

    A finding moves from a cautious report to an abstract, a summary and a headline, losing qualifiers at each step. The claim widens while its evidence stays the same, until it exceeds what any source supports.

    Mechanism

    Single-source dependence

    Many records rest on one upstream source cited by several intermediaries. Counting the intermediaries makes the evidence look plural and independent when it is one source repeated.

    Mechanism

    Confidence without basis

    A confidence word such as likely or high is attached without saying what it rests on. Readers in different fields interpret the word differently, so one label carries different meanings to an editor, a funder and a court.

    05Key terms

    Terms used on this page.

    Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.

    TermDefinition
    Evidence labelA tag on an assertion naming the kind of evidence behind it, such as observed, officially reported or modelled.
    Claim creepThe gradual strengthening of a claim as it is repeated, beyond what its original evidence supports.
    Single-source dependenceReliance of an assertion on one source, however often it is cited.
    06Indicators

    What is measured, and how well.

    Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.

    IndicatorUnitCadenceSource typeLabel
    Assertions with an evidence classshare of assertionsmonthlySchema validationOBSERVED
    Assertions by evidence classcount by classquarterlyRegistry recordsOBSERVED
    Assertions resting on a single sourceshare of assertionsquarterlyProvenance graphOBSERVED
    Confidence statements with a stated basisshare of confidence statementsquarterlyCuration reviewOBSERVED
    Class reassignments after reviewcountquarterlyReview recordsOBSERVED
    Agreement between independent classifiersagreement coefficientper auditDouble-coding auditESTIMATED
    Claims exceeding their evidence classcountmonthlyClaim-to-evidence auditOBSERVED
    07Canvas

    From sources to decisions.

    The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.

    Pipeline canvas · Evidence classes as a run graphDesign, not a record
    Evidence classes: systematic evidence synthesisA question is framed with its owner and a protocol registered; records are searched, screened and checked for eligibility by two reviewers; data are extracted, synthesised and graded for certainty before a brief is written. Design of the process, not a record of a run.

    Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.

    08Sources

    Where the evidence comes from.

    Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.

    SourceWhat it givesLicence class
    GRADE handbookA method for rating the certainty of evidence and the strength of recommendationsFree to read, GRADE Working Group terms
    Cochrane Handbook for Systematic Reviews of InterventionsMethods for assessing risk of bias and synthesising evidenceFree to read online, Cochrane copyright
    IPCC guidance note on consistent treatment of uncertaintiesCalibrated language for confidence and likelihood in assessmentsFree to read, IPCC terms
    Evidence and Conclusion Ontology (ECO)A controlled vocabulary of evidence types used in scientific curationOpen ontology, free to reuse
    Oxford CEBM levels of evidenceA hierarchy of evidence types for clinical questionsFree to read, attribution
    Campbell Collaboration methods guidanceMethods for evidence synthesis in social and economic policyFree to read, Campbell terms
    09Decisions

    Who decides, and what the evidence serves.

    Nexus Registry prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.

    Who decidesThe questionEvidence this page serves
    Guideline panels and systematic reviewersHow much weight an assertion can bear in a recommendationEvidence class, certainty rating and independence of the sources behind it
    Funders and assessment panelsWhether reported outcomes are evidenced or only declaredClass labels separating observed outcomes from self-reported and planned ones
    Journal editorsWhether a manuscript's claims match the class of evidence it citesEvidence class of each cited record and any single-source dependence
    Regulators and public bodiesWhether evidence is strong enough to justify a rule or an interventionClass, confidence basis and reliance limits for each supporting record

    Outputs this topic produces

    • An evidence class assigned to each assertion and carried into every view and export
    • A glossary of classes stating what each supports and what it does not
    • Reliance notes marking assertions that rest on a single source
    • Confidence statements with their stated basis and the reviewer who set them
    10Core questions

    What experts ask about evidence types.

    • How should a classification separate the source of a claim from its reliability?
    • How can a label survive aggregation, when estimates are mixed with observations?
    • How should confidence be communicated to non-specialists without misleading them?
    • When is a scenario mistaken for a forecast, and how is that prevented?
    • What should a record say when the evidence type is unknown?
    11Mechanisms

    How evidence loses its label.

    Evidence is most often misused not because it is wrong but because it is read as something it is not. A modelled estimate printed in a table beside official statistics acquires their apparent authority. A scenario designed to explore a possibility is quoted as a prediction. Assessment bodies in climate science, public health and statistics have each developed calibrated language for confidence and likelihood for this reason.

    The Registry uses the evidence labels shared across the programme: Observed, Officially reported, Institution-reported, Estimated, Modelled, Forecast, Scenario, Expert judgement and Unknown. A label names a source type. Officially reported means reported by an official source; it is not a claim of endorsement. Estimates stay labelled as estimates and never replace official figures.

    12Methods and limits

    Classifying and qualifying evidence.

    1. 01

      Source type

      The label records how the evidence was produced, separately from any judgement of quality.

    2. 02

      Reliance limits

      Each record states the uses it can and cannot support, such as the geographic scale or period for which it holds.

    3. 03

      Confidence

      Where a method yields uncertainty, the record carries it, drawing on statistical practice from the STEM Commons. See data engineering, interoperability and stewardship for the data side.

    4. 04

      Limits

      Any classification simplifies. Mixed evidence needs the most cautious label of its parts, which can understate strong findings, and labels depend on honest declaration by issuers.

    13Methods

    How it is studied, and what the methods cannot say.

    1. Data engineering, interoperability and stewardshipSchema-validated ingestion · Persistent identifier reconciliation · Lineage capture in pipelinesApplied here
      Canonical · STEM Commons
    2. Cybersecurity and cryptographyTamper-evident record history · Signed exports and releases · Threat modelling of edit pathsApplied here
      Canonical · STEM Commons
    3. Digital identity and public digital systemsIssuer authentication and authority · Contributor disambiguation by the personApplied here
      Canonical · STEM Commons
    14Questions

    Questions and answers.

    Is a declared assertion worthless?
    No. A declaration is the issuer's own statement, and for some facts, such as an owner's intent, it is the right evidence. It is labelled so readers know it has not been independently checked.
    Why can confidence words mislead?
    Because likely or high confidence mean different things across fields. Stating the basis, such as the agreement of independent sources, lets readers judge the word for themselves.
    Can an assertion's class change?
    Yes. New evidence, review or correction can raise or lower it. Each change is recorded with its reason, and the earlier class stays visible in the record's history.
    Why are many citations not many sources?
    Because several records can repeat one upstream source. The provenance graph shows whether supporting records are independent or share an origin, which matters more than their count.
    Is Officially reported a stronger label than Modelled?
    It names a different source, not a ranking. An official figure can be revised, and a model can be well validated. The record states the limits of each.
    Why keep an Unknown label?
    Because pretending to know a source is worse than saying it is unknown. An Unknown label tells readers to treat the evidence with care.
    Can a record carry more than one label?
    A composite record states the label of each part, and its headline label is the most cautious one.
    Related

    Around Nexus Registry.

    Nexus Registry

    Bring your expertise to this field.

    The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.

    Write to the team See all contact routes
    Have questions?