Top Rated ranks sellers by their share of positive reviews (9 or 10 out of 10) among the reviews BiggyIndex has recorded for them, not the lifetime total Little Biggy shows. Every seller starts with 40 imaginary reviews, 35 of them positive, and we use the cautious end of a 95% confidence range (the Wilson lower bound), so a few perfect reviews can’t outrank hundreds of good ones. Ratings of 6–8 count towards the total but not as positive, and 5 or below count as negative.
Needs Review lists sellers with at least 30 reviews and 2 negatives whose negative share is 4% or more, or whose positive share is 85% or less, worst first; they are kept out of Top Rated. The “Last 14 days” tab applies the same rules to reviews from the last 14 days (at most each seller’s latest 150), with thresholds of 10 reviews and 5%. Only sellers with live listings in this market are ranked, and ties go to the most recent review.
Delivery time, review recency, account age and community endorsements or reports don’t affect the ranking yet. The formula is open source on GitHub, so anyone can check it or suggest a better one.
