What 15 Million Readers Reveal About the Human Condition

Tracing collective mood, reading psychology, and cultural aspiration through the largest public dataset of book ratings.

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The Story in 229 Million Ratings

A book rating is a uniquely honest data point. Nobody finishes a 400-page novel for algorithmic visibility. When millions of such signals are aggregated over time, they trace the emotional currents of a population.

We analyzed the UCSD Book Graph — 2.36 million books, 229 million interactions, and 15.7 million full-text reviews — to make those currents visible.

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Genre Popularity Over Time (2010–2017)

Each layer represents a genre's share of highly-rated books. Hover to inspect; vertical markers denote world events.

Do Readers Get Harsher Over Time?

We track individual users who have rated at least 30 books and plot their average rating as a function of how many books they've read. The result: a clear downward drift.

Power readers — those with 200+ books — rate roughly 0.3 stars lower on average than when they first started reviewing.

Average Rating by Books Read

Each point shows the mean rating at that reading milestone. Shaded area is ±1 std deviation.

What We Want to Read vs. What We Actually Read

Goodreads lets users shelf books as "to-read" without ever opening them. By comparing shelf-to-read counts with actual read-through rates, we expose a fascinating gap.

Classic Literature has the highest aspiration-to-reality gap — heavily shelved, rarely finished. Meanwhile, Romance readers follow through at nearly twice the rate of any other genre.

Aspiration vs. Reality by Genre

Left bars = shelved "to-read"; right bars = actually read. Gap reveals which genres are aspirationally hoarded.