P2P Index
P2P Index publishes reference values for sports and trading cards: median per card and grade, range, trend and the real sales behind them. Free to consult, public methodology.
What P2P Index publishes
For a given card and grade, P2P Index publishes a dated median value, the sample size behind it, its evolution over time and the matching active listings. Every page states when it was last computed: an undated value is worthless.
The methodology is public and stable: robust median of completed sales over a rolling window, outlier trimming, strict separation by grade. P2P Index never blends a graded sale and a raw sale into one number.