GCRI · Food Nexus
Methods and uncertainty
The methods Food Nexus relies on: their equations and assumptions, the data they need, how they are validated and the limits of what they can show.
Methods and uncertainty in five parts.
The methods in use.
- 01Agricultural, soil and food scienceCrop simulation for seasonal yield risk · Yield gap and nutrient limitation analysisApplied here
- 02Ecology and biodiversity sciencePollination and natural pest control · Fisheries and aquatic food websApplied here
- 03Earth observation and remote sensingCrop condition monitoring · Crop type and area mapping · Irrigation and water productivityApplied here
- 04Spatial statistics and geostatisticsSmall-area estimation of food insecurity · Digital soil mappingApplied here
- 05Forecasting and time-series analysisSeasonal production outlooks · Staple price forecasting · Anticipatory action triggersApplied here
- 06Optimisation and operations researchHumanitarian supply and prepositioning · Strategic reserve designApplied here
- 07EconometricsPrice transmission and market integration · Effects of trade policyApplied here
- 08Hydrology and water scienceIrrigation supply and demand · Agricultural drought monitoring · Flood exposure of croplandApplied here
- 09Biotechnology platformsBreeding for stress tolerance · Rapid diagnostics for pests and diseaseApplied here
- 10Water and environmental engineeringIrrigation and drainage design · Safe wastewater reuse in agricultureApplied here
Each method, its role in this field and how it is checked.
- Agricultural scienceRole hereAgricultural, soil and food science is the core discipline of this platform.Checks appliedMulti-model ensembles; Out-of-sample yield testing; Trial design review; Survey reconciliation
- EcologyRole hereEcology explains the living systems that food depends on and affects: pollinators, natural enemies of pests, soil organisms, fisheries, wetlands and the landscapes around farms.Checks appliedIndependent survey validation; Sampling bias correction; Mechanism testing
- Earth observationRole hereSatellites observe cropland every few days and across borders: greenness, water stress, planted area, flooding, burnt land and land cover change.Checks appliedAccuracy assessment; Cross-sensor consistency; Cloud and gap reporting
- Spatial statisticsRole hereSpatial statistics turns sparse surveys, soil samples and market prices into maps with stated uncertainty.Checks appliedSpatial cross-validation; Uncertainty maps; Scale and zoning tests
- ForecastingRole hereForecasting gives food systems lead time: seasonal production outlooks, projections of lean-season food insecurity, staple price outlooks and pest alerts.Checks appliedHindcast verification; Reliability and sharpness; Rolling-origin evaluation; Trigger performance record
- OptimisationRole hereOptimisation and operations research help allocate scarce food, water, storage and transport under constraints.Checks appliedFeasibility and simulation; Comparison with past decisions; Sensitivity to assumptions
- EconometricsRole hereEconometrics estimates how food prices, incomes, trade and policies respond to shocks.Checks appliedIdentification review; Robustness across specifications; Out-of-sample checks
- HydrologyRole hereHydrology connects food production to the water that sustains it: rainfall, soil moisture, river flows, reservoirs and groundwater.Checks appliedSplit-sample calibration; Water balance closure; Indicator agreement
- BiotechnologyRole hereBiotechnology platforms in food and agriculture include marker-assisted and genomic breeding, gene editing, biological inputs, diagnostics for plant and animal disease, and fermentation-based food production.Checks appliedIndependent replication; Regulatory review; Post-release monitoring
- Environmental engineeringRole hereWater and environmental engineering designs the infrastructure food systems run on: irrigation and drainage, wastewater reuse, water and effluent treatment in processing, and the refrigerated stores and transport of the cold chain.Checks appliedDesign standard review; Field calibration; Incident reconstruction
How the process runs.
Process
Methods and uncertainty: PRISMA 2020 review reporting
PRISMA 2020 is a reporting guideline for systematic reviews; the steps follow its checklist, not a mandated sequence, and no Nexus document adopts it.
01 Plan
- 01Registration and protocolRecord · The review teamThe guideline asks for registration details, access to the protocol and any amendments.
- 02Eligibility criteriaRecord · The review teamThe guideline asks for the inclusion and exclusion criteria and how studies were grouped.
02 Find and select
- 03Search: sources and strategiesStep · The review teamThe guideline asks for the information sources and the full search strategies. It does not fix which sources are used.
- 04Selection of studiesStep · The review teamThe guideline asks how studies were judged eligible, including how many reviewers screened. It does not fix the number of reviewers.
- 05Flow diagramRecordThe flow diagram shows the number of records found, the number of studies included and the reasons for exclusion.
03 Analyse
- 06Data collectionStep · The review teamThe guideline asks how data were collected from reports and which data items were sought.
- 07Risk of biasStep · The review teamThe guideline asks for the methods and tools used to assess risk of bias.
- 08SynthesisModel · The review teamThe guideline asks for the effect measures and the synthesis methods. It does not prescribe meta-analysis.
- 09Certainty of evidenceStep · The review teamThe guideline asks for the methods used to assess certainty, and reports the result per outcome. It does not name a grading scale.
04 Report
- 10Review reportRecordThe guideline helps authors report why the review was done, what they did and what they found.
ReportsOutline of an externally published reporting guideline, not a Nexus process and not a record of operation. PRISMA 2020 mainly covers reviews of intervention effects. No Nexus page names it. Every programme is at service level R0.
Where uncertainty in food system analysis comes from, and how it is shown.
| Source | Why it matters here | How it is reported |
|---|---|---|
| Crop model structure | Models diverge most under heat stress and in their response to carbon dioxide | Multi-model ensembles following AgMIP protocols |
| Production statistics | Smallholder output and subsistence production are estimated, not measured | Evidence label on each figure; survey basis stated |
| Stocks | Many countries do not publish public or private stock levels | Ranges and stated assumptions in stocks-to-use ratios |
| Price transmission | Depends on policy, exchange rates and market integration that change quickly | Scenario sets rather than single elasticities |
| Household access | Food security outcomes rest on surveys with long gaps | IPC consensus process and its confidence levels |
An acute food insecurity figure is never shown without its classification system, the analysis period and whether it is a current estimate or a projection.
How uncertainty is reported.
- 01
State assumptions
Each analysis lists its assumptions and the data it depends on.
- 02
Quantify where possible
Ranges and confidence are reported alongside central estimates.
- 03
Validate and compare
Models are checked against observations and, where possible, against other models.
- 04
Publish limits
What an analysis cannot show is stated beside what it can.
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
Are the methods open?
Contribute evidence from this page.
Reports is the Consortium’s quarterly publication. What you know about this subject can become evidence, a case or a correction in the next edition, credited to you and published under CC BY 4.0 where it is your own work.
- EmailGateway GW-GCRISend it from this pageEvidence, a correction, a case, a method, a review, a translation or profile input. It arrives tagged with this page, so the editor who owns it receives it.
- ZenodoOpen depositDeposit it and submit to the communityPublish your own record on Zenodo with your ORCID iD, then submit it to the Reports community there. Curators review it; the DOI stays yours.
- ReportsGCRISee every way to contributeThe contribution types, how each is reviewed, what credit you receive, the licence and what is never accepted.
Never send personal data, sensitive infrastructure detail or anything you have no right to share. A contribution is reviewed before use; sending it confers no authorship or editorial rights, and sponsorship never buys a finding.
Bring a method, a dataset or a question.
Information and enquiries are open today. 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.
Legal documents.
Maps, data and figures on this site are shown for context and general information. They are not advice, forecasts or warnings; the limits of the information are set out in the Disclaimers and Data Notices.