Book
This Mighty Scourge: Perspectives on the Civil War
Two parallel scores from 4 calibrated reviewers and 18 raw-average reviewers.
Z-normalized corrects for reviewer bias (every reviewer re-centered onto their personal scale). Raw average uses simple mean across the broader pool including stddev=0 reviewers. The 17-point gap is the rating-inflation signature for this title — the casual crowd liked it more than discriminating reviewers (a classic inflation pattern).
Where this book sits
Z-normalized percentile · 5,285 ranked books
| Mean reviewer z-score | -0.835 |
|---|---|
| Calibrated raw-mean rating | 4.00 /5 |
| Broad raw-mean rating | 4.56 /5 |
| 90% CI-floor (z) | -1.658 |
| Reviewers (calibrated / broad) | 4 / 18 |
Summary
This Mighty Scourge: Perspectives on the Civil War sits at the 8th z-normalized percentile across 5,285ranked books. The z-percentile differs from a raw star average because Rankquant subtracts each reviewer's personal baseline before aggregating — so a reader who rates everything 5 stars carries less weight than one who rates discerningly. Raw-average percentile is 25; the gap between the two measures how much bias-correction changes this title's standing. How percentiles are computed.
Pipeline applied to this title
The math, in this order
4 reviewers with rating variance re-centered onto a personal z-scale.
Mean z = -0.835. Broad raw mean = 4.56/5.
90% CI-floor = -1.658. Thin samples penalized.
Global 7.5. Z-track and raw-track ranked separately.
Similar percentile
