# Methodology

- Source database: `cisbox:/home/m09w/ene_plans/data/db/plans.duckdb`
- Snapshot date: `2026-04-20`
- Release: `2026-04-20-v0.1.0`
- Export basis: exact daily snapshot rows; no interpolation between scrape dates.
- Geographic grain: unique plan/distributor/jurisdiction combinations derived from `plan_postcodes`; postcode duplicates are collapsed only in `tariff_plans.csv` and retained in `plan_postcode_availability.csv`.
- Jurisdiction is derived from Australian postcode ranges and retained as `UNKNOWN` where it cannot be inferred.
- Prices and source text are exported without bill modelling or GST transformation.
- Child pricing tables are joined to each geography in which the plan appears.
- Classification flags in `tariff_plans.csv` use source fields plus conservative name/term text matching. They are convenience filters and should be audited against eligibility and terms for consequential use.
- CSV encoding: UTF-8, comma-delimited, header row, empty fields represent null values.
