Book
My First Guitar: Learn To Play: Kids
Two parallel scores from 3 calibrated reviewers and 5 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 41-point gap is the rating-inflation signature for this title — discriminating reviewers liked it more than the casual crowd.
Where this book sits
Z-normalized percentile · 5,285 ranked books
| Mean reviewer z-score | +0.461 |
|---|---|
| Calibrated raw-mean rating | 5.00 /5 |
| Broad raw-mean rating | 4.80 /5 |
| 90% CI-floor (z) | -0.488 |
| Reviewers (calibrated / broad) | 3 / 5 |
Summary
My First Guitar: Learn To Play: Kids sits at the 89th 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 48; 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
3 reviewers with rating variance re-centered onto a personal z-scale.
Mean z = +0.461. Broad raw mean = 4.80/5.
90% CI-floor = -0.488. Thin samples penalized.
Global 89.1. Z-track and raw-track ranked separately.
Similar percentile
