How the Cost Index is calculated

Three separate layers

1. Raw submissions preserve what was sent, its source type and validation flags.
2. Validated observations contain accepted records suitable for analysis.
3. Aggregated statistics are precomputed public medians and ranges.

Validation

Checks cover required fields, malformed amounts, configured plausible ranges, rate limits and possible duplicates. Unusual values are flagged rather than automatically deleted; a high shoeing price may represent genuine remedial work.

Statistics

The primary public statistic is the median. We also compute the 25th and 75th percentiles, mean for internal review, sample count and reporting range.

• Fewer than 5 accepted reports: no statistic
• 5–14: limited data
• 15–49: normal coverage
• 50 or more: strong dataset

When local coverage is too small, the geographic fallback is county → region → UK.

Index basket

Methodology v1 uses a weighted routine-cost basket: livery 45%, forage 15%, farrier 12%, feed 10%, bedding 8%, healthcare 5% and other routine services 5%. The base period is 100.0.

Historical integrity

Published index snapshots store the period, index value, components, publication time and methodology version. A later method does not silently rewrite an older snapshot.

Provenance

Public figures state the median, typical range, report count, date range and included source types. Suspected duplicates and rejected values are excluded.