# Public evidence review — 3 November 2026

## How to use this register

This is an evidence inventory for designing and calibrating the Harvest League teaching game. It does **not** establish the real market size, buyer demand, transaction prices, operating costs, or competitor actions for the Strawberry Corridor Operating Company (SCOC). Only measured operating records, dated written quotes, orders, invoices, and contracts can establish those inputs for the pilot.

The linked public-evidence CSV retains the record-level source, observation period, confidence, permitted use, and limitation for each entry. Use those fields together; a low-confidence listing should not become a base-case transaction input.

## Evidence available

| Area | Public evidence in the register | Appropriate use |
|---|---|---|
| Farm supply | Individual Plateau farm output and area reported in interviews; one future expansion forecast | Plausibility bounds for farm-level scenarios only; not a regional supply curve |
| Buyer access | Reports of one farm with an offtaker, settlement after successful delivery, and failed buyer interest | Justifies modeling contracts, collections, and downside off-take risk; provides no volumes or probabilities |
| Logistics | Announced weekly air-lifting capacity, an old cold-storage study, and an advertised reefer rate for another route | Scenario context and quote-comparison prompts; not a current Jos–Abuja or Jos–Lagos tariff |
| Costs | NBS publishes a state retail diesel series; the May 2026 Plateau value is listed as ₦3,576.40/litre in an NBS-derived time-series view. The NBS catalogue lists the May 2026 spreadsheet, but that file was not parsed in this review. | Use only as a dated fuel-price signal. Verify the exact row in the NBS workbook, and do not convert it to ₦/kg freight without vehicle, load, route, and return-trip data. It is not SCOC's bulk energy or delivered cost. |
| Market prices | Online asking prices, one conflicting carton listing, a retail pack without mass, and a public price-data portal | Listing-quality and observation-method examples; do not treat as cleared transaction prices |
| Sector context | A historical Plateau grower survey | Context for farmer constraints, not a current nominal cost benchmark |
| Trade context | WITS reports 815,510 kg of fresh strawberry imports in 2024 and 234,900 kg in 2025 (HS 081010) | Import-flow context only. The reported 71.2% year-over-year decrease is not domestic demand growth and should be checked for reporting revisions/comparability |
| Plateau sector context | A historical state plan lists strawberry among Plateau crops and describes low-scale smallholder production and potential out-of-state markets | Qualitative policy context only; it provides no strawberry-specific market size or current buyer orders |
| Product risk | A Plateau exploratory survey identified 12 fungal isolates in strawberry disease samples from four farms/four markets during the 2022–23 crop season | Supports the need to record batch quality and handling; does not estimate a commercial-lot rejection or shrink rate |

## What remains unknown

- Addressable weekly demand by buyer, route, grade, packaging, and season.
- Actual SCOC order quantities, accepted/rejected weights, realized prices, claims, and payment dates.
- Supplier commitments and actual harvested, delivered, graded, and saleable kilograms.
- Measured loss by stage, temperature excursion, route, storage duration, and product grade.
- Current packaging, power, cold-room, reefer, labor, maintenance, commission, tax, and financing costs.
- Competitor capacity, offers, prices, service levels, and repeat buyer relationships.
- A complete domestic production and import-replacement market size, and what share SCOC could serve.

## Additional internet check — 3 November 2026

- The NBS microdata catalogue lists an **Automotive Gas Oil (diesel) Price Watch, May 2026** workbook. It says its survey covers outlets in all 774 LGAs and reports state/FCT averages. A current NBS-derived time-series view reports Plateau at **₦3,576.40/litre**, up sharply from the prior year; the NBS spreadsheet itself was not parsed here, so verify the exact row before importing it as a numeric model input. Even when verified, this is household retail diesel, not a refrigerated truck quote or cost per delivered kg. [NBS AGO catalogue](https://microdata.nigerianstat.gov.ng/index.php/catalog/158/related-materials) · [NBS-derived state series](https://dataminal.com/nigeria/diesel-prices).
- WITS/UN Comtrade reports **815,510 kg** of Nigerian fresh-strawberry imports in 2024 (US$1.327m) and **234,900 kg** in 2025 (US$0.531m). This is cross-border trade flow, not domestic production, buyer orders, or total addressable demand. The sharp year-to-year change should be treated cautiously pending revisions and coverage checks. [WITS 2024](https://wits.worldbank.org/trade/comtrade/en/country/NGA/year/2024/tradeflow/Imports/partner/ALL/product/081010) · [WITS 2025](https://wits.worldbank.org/trade/comtrade/en/country/NGA/year/2025/tradeflow/Imports/partner/ALL/product/081010).
- Online Jos advertisements include a **₦35,000 / 5 kg** seller ask (₦7,000/kg) and a conflicting listing with a **₦1,500 headline** but **₦7,500 / 5.5 kg** in its text (about ₦1,364/kg). These are unverified asking prices with unclear grading, freshness, delivery, and availability, not transaction records. [Jiji listing](https://jiji.ng/jos/meals-and-drinks/strawberry-hlEI5BKrVsbiTSW0h9NKcOg8.html) · [AgroHUB listing](https://agrohub.ng/en/board/m-482/).
- The Nigerian e-Agriculture Portal has interactive production-by-produce and consumption-by-produce selectors, but this review did not retrieve a strawberry-specific time series from it. [National e-Agriculture Portal](https://eagriculture.gov.ng/FoodSecurity/NationalProductionByProduce.aspx).

These checks still did **not** uncover public buyer-level orders, accepted/rejected deliveries, realized transaction prices, settlement dates, or strawberry-specific Jos–Abuja freight invoices. The strongest next step is a small original observation set: dated buyer quote/order samples, at least two route quotes, and lot weights at intake and receipt. Keep each public proxy in the register with its scope and confidence rather than using it to fill missing actuals.

## Calibration priorities

1. Start with a dated order ledger and buyer acceptance/collection records.
2. Weigh product at grower pickup, packhouse intake, dispatch, and buyer receipt; reconcile the differences by batch.
3. Capture written, route-specific freight and cold-storage quotes, then replace them with invoices as the pilot runs.
4. Track contracted vs delivered grower volume and payment dates.
5. Record observed public prices with pack weight, grade, date, market, and delivery term.
6. Preserve each actual round's decisions and results. Fit assumptions on earlier rounds and validate on later rounds not used to set the assumptions.

## Source references

Record-level links and limitations are in [`data/calibration/public_evidence.csv`](../data/calibration/public_evidence.csv). Public sources cited there include Daily Trust/Trust Radio interviews, an IFPRI-reported ColdHubs study, Nigerian Bureau of Statistics materials, online market listings, a Plateau strawberry disease survey, Plateau State's historical strategic plan, and World Bank WITS trade data sourced from UN Comtrade. WITS reports Nigeria imported 815,510 kg of fresh strawberries valued at US$1.32658m in 2024 under HS 081010 and 234,900 kg in 2025. The reported quantity fell 71.2%; this is a change in imports, not a measure of domestic consumption or demand. The years may be affected by reporting revisions or coverage differences, so the change is not used to scale game demand. The Plateau plan is historical and qualitative. The Plateau disease survey examined four farms and four markets in the 2022–23 crop season and identified 12 fungal isolates associated with strawberry disease samples; it does not provide a representative rejection rate for commercial shipments. The specific source and limitations control the permitted use of each figure.

## Model status

The playable release uses explicit game-design coefficients and scenario switches. None of the public evidence listed here validates those demand-response or scoring equations. The game should display those rules as assumptions until a pilot dataset supports calibration and an out-of-sample forecast check.