Unlike earlier studies that tried to detect AI text from short book previews alone, the researchers classified each book based on its full text. They used the Pangram v3.3 detector, whose developers report a false-positive rate of 0.04 percent. Pangram 4 has since been released. Books were sorted into three bands based on the share of text flagged as AI-generated: none, light (up to 25 percent), and substantial (over 25 percent).
Big catalog presence, below-average sales
Books with substantial AI content make up 20 percent of the catalog studied but account for only 12.1 percent of sales and 11.3 percent of revenue. Books with no detected AI text represent 62.9 percent of the catalog and generate 72.5 percent of revenue. At first glance, that seems to confirm the view that AI books remain low-quality "slop" stuck at the bottom of the market.
Books with substantial AI content make up 20 percent of the catalog but account for only 12.1 percent of sales and 11.3 percent of revenue. | Image: Chakrabarty et al.
The study shows that this view misses the real market dynamics, though. Between Q1 2023 and Q1 2026, the cumulative catalog grew 38.3x while the number of titles selling per quarter grew 19.2x. Quarterly revenue only grew 8.9x. Far more books are now competing for a revenue pool that's growing much more slowly.
