Book
Tadpole to Frog (National Geographic Kids Readers, Level 1/Co-Reader): Animals Grow Up
Two parallel scores from 3 calibrated reviewers and 4 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.
Where this book sits
Z-normalized percentile · 5,285 ranked books
| Mean reviewer z-score | -2.808 |
|---|---|
| Calibrated raw-mean rating | 3.00 /5 |
| Broad raw-mean rating | 3.50 /5 |
| 90% CI-floor (z) | -3.757 |
| Reviewers (calibrated / broad) | 3 / 4 |
Summary
Tadpole to Frog (National Geographic Kids Readers, Level 1/Co-Reader): Animals Grow Up sits at the 0th 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 2; 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 = -2.808. Broad raw mean = 3.50/5.
90% CI-floor = -3.757. Thin samples penalized.
Global 0.1. Z-track and raw-track ranked separately.
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