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 retailer prices every day for a canonical catalog of golf equipment, observed daily, every retailer. Prices come from retailer and affiliate feeds, not from scraping public pages. Only prices in US dollars between $1 and $20,000 are used.
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
Every observed price is a snapshot with an id. The id appears in /v1/prices/history rows and in the audit trail, so a cited number can be traced to its source row.
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.