Price index methodology
The Golf Equipment Price Index measures how prices for the same golf products move from month to month across the retailers GolfData tracks.
Data
GolfData records dated price observations for a canonical catalog of golf equipment from tracked retailer and affiliate sources. Coverage and update times vary by source. Only prices in US dollars between $1 and $20,000 are used in this index.
Product monthly price
For each product and each day, we take the lowest price offered by any tracked retailer. A product's monthly price is the median of those daily lows.
Category index
A category compares the products that have a monthly price in both the base month and the edition month. Each product's price relative is its edition month price divided by its base month price. The category index is the geometric mean of those relatives, times 100, the Jevons formula used for matched product price indexes. The base month is June 2026 = 100. A category is published only when at least 50 products qualify. The base and edition medians of the same products are published alongside the index for context.
Other figures
- Median price: the median monthly price across every product priced in the edition month.
- Below list: the share of products with a known list price whose monthly price is under it.
- Median markdown: among products below list, the median discount from list price.
- Retailer spread: for days when two or more retailers priced the same product, the gap between the highest and lowest price as a share of the lowest, taken as a median per product and then per category.
Integrity levels
Every field traced to a source. Cite it with confidence.
Key fields traced, the rest unconfirmed. Check the fields you cite.
Needs human review before it is cited or shipped.
Snapshot id
The public history endpoint returns retailer, price, and recorded at time for each selected row. It does not return the internal snapshot ID. Include the product ID, retailer, and observation date when reporting a questionable row so we can locate the underlying evidence.
Corrections and limits
A dated observation is evidence of a recorded asking price, not a promise that a retailer still sells the exact variant at that price. Source coverage, stock, and refresh times vary. See the correction and withdrawal policy to report an incorrect product match, price, stock state, source attribution, or link.
Exclusions
Products that could not be matched to a canonical product, duplicate listings merged into another product, and categories outside the published set (apparel, accessories, uncategorized items) are excluded. Retailer names are not published in the index.
Citation
Free to cite with a link to golfdata.co. Each edition ships as CSV and JSON. The index files are licensed under Creative Commons Attribution 4.0. Questions: hello@golfdata.co.