All markets · 90-day comparable periods
Empty time buckets are shown as zero and retain their sample size; they are not interpolated by AI.
These are the records counted in the current prevalence numerator.
C. A. Mercer
Inspect evidenceLeah Marr
Inspect evidenceD. M. Harrow
Inspect evidenceKate Linden
Inspect evidenceRed / black palette increased from 0% to 15.4% across comparable 90-day windows, a 15.4 percentage-point upward movement. The feature currently appears in 4 tracked market segments.
Amazon New Releases has the highest current prevalence at 16.7% (1 of 6), while Amazon Bestsellers is lowest at 12.5% (1 of 8).
Inspect the matching covers alongside non-matching covers from the same source types. Look for whether red / black palette co-occurs with particular typography, imagery, colour, or subgenre choices before treating this as a durable convention.
Current window: 4 matching covers from a sample of 26.
Previous window: 0 matching covers from a sample of 0.
15.4 percentage points of measured upward movement.
This describes the tracked genre sample only. It does not establish why the feature changed, whether it improves sales, or whether it represents the entire book-cover market.