# Cheddar Check, Issue 1: October 2026: data dictionary

Files in this directory hold the record behind the edition. `data.csv` is source-reported data as parsed from the retained files; `measures.csv` is what the edition quotes, including the figures Field Assembly calculated; `numbers.json` and `evidence.json` are the same record as kept in the repository. Values keep the precision they were parsed or computed at; the edition text rounds for display.

Data run: `2026-10-18T145249Z`. Information available as of 18 October 2026. Rows in data.csv: 3286.

License: Field Assembly's tables, calculations and documentation here are CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/); cite the edition. Files under `evidence/` are third-party source material and keep their publishers' terms.

## data.csv

One row per series and period, from the data run named above. A series is a monthly (`YYYY-MM`) or weekly (`YYYY-MM-DD`, week ending) series; forecast-table rows from USDA ERS carry no period and are labeled by attribute text in `series_id`.

| Column | Meaning |
|---|---|
| series_id | Identifier. BLS series codes are used as published (for example `WPU02230503`); Field Assembly identifiers are lowercase with underscores and say what was derived (for example `..._usd_per_lb` from value divided by quantity) |
| series_title | Plain description, with the reporting basis (not seasonally adjusted, preliminary, derived) |
| period | Observation period. Monthly `YYYY-MM`; weekly `YYYY-MM-DD` is the week-ending date; empty for forecast-table attributes |
| value | Numeric value as parsed. Empty when the source published a non-numeric marker; the marker is kept in `notes` |
| unit | Unit as reported or as derived: `index`, `USD per lb`, `kg`, `lb`, `USD`, `Percent`, `Percent change`, `cents per dozen` |
| source_id | The source in `sources.json` and on the methodology page |
| source_label | The source's class: OFFICIAL STATISTIC, OFFICIAL MARKET REPORT, or FOOD-COST INDICATOR |
| source_url | URL fetched (the final URL after any redirect) |
| captured_at | Retrieval time, UTC, ISO 8601 |
| evidence_path | The retained file, byte for byte, under `evidence/` in this directory |
| sha256 | SHA-256 of that file |
| notes | Preliminary flags, derivation arithmetic, restatement notes, or the source's own marker text |

Missing values: an empty `value` cell means the source published no numeric value for that period. No value is imputed, interpolated, or carried forward.

## measures.csv

Every figure in `numbers.json`, flattened to one row per leaf with a dotted key. `kind` says whether the row is a Field Assembly calculation or a value or label carried from a source. Calculations:

- `yoy_pct`: (latest − same period a year earlier) ÷ same period a year earlier × 100, rounded to one decimal. The same month for monthly series; for weekly series the week ending nearest to 52 weeks earlier, within four days.
- `vs_two_years_pct`: the same against two years earlier.
- `change_pct` on peaks, annual totals and year-to-date sums: the same formula on the two values named beside it.
- Unit values: dollars divided by quantity, with kilograms converted at 2.20462262 lb per kg where the series says `per lb`. The arithmetic is in the `notes` column of data.csv.
- Annual and year-to-date sums add the monthly rows in data.csv for the months named.
- Averages over a window are unweighted means of the weeks listed beside them.

Index series are indexes, not prices. A change in an index is a change in the index.

## Sources in this data run

| source_id | Source | Class | Page |
|---|---|---|---|
| `bls` | U.S. Bureau of Labor Statistics: PPI, CPI and average price series (public API v2) | FOOD-COST INDICATOR (index) and OFFICIAL STATISTIC (average retail price) | https://data.bls.gov/timeseries/WPU023302 |
| `ndpsr_block` | USDA AMS: National Dairy Products Sales Report, 40-pound block cheddar (Datamart report 2993) | OFFICIAL STATISTIC (weekly weighted-average wholesale price under mandatory reporting, USD per lb) | https://mpr.datamart.ams.usda.gov/menu.do?path=Products%5CDairy%5CNational%20Dairy%20Products%20Sales%20Report |
| `ndpsr_barrel` | USDA AMS: National Dairy Products Sales Report, 500-pound barrel cheddar (Datamart report 2993) | OFFICIAL STATISTIC (weekly weighted-average wholesale price under mandatory reporting, USD per lb; publication ceased mid-2025) | https://mpr.datamart.ams.usda.gov/menu.do?path=Products%5CDairy%5CNational%20Dairy%20Products%20Sales%20Report |
| `ams_dmn_cheese` | USDA AMS: Dairy Market News weekly report, CME cheese (PDF) | OFFICIAL MARKET REPORT (CME cheese cash market as reprinted by USDA) | https://www.ams.usda.gov/market-news/dairy-market-news-weekly-printed-reports |
| `usda_ers_fpo` | USDA ERS Food Price Outlook (CPI forecast table) | FOOD-COST INDICATOR (official forecast table) | https://www.ers.usda.gov/data-products/food-price-outlook |

Reports issued separately by one institution are not independent corroboration of each other.

## evidence/

The retained source files with their HTTP response headers (Set-Cookie redacted at capture), and `capture.json` for each source with URL, time and SHA-256. Under `evidence/anchors/`: the timestamp chain entry that covers these files, its manifest of hashes, and the RFC 3161 tokens. A token attests that the entry hash existed at the stated time; it does not attest that any source's figure was correct.