Readers Saying It's Well Written Doesn't Mean They Learned: What Self-Ratings, Liking, Viewing Time, Practice Scores, and Proxy Metrics Each Measure
In a crossover experiment in a Harvard physics course, the class in which students scored 0.46 standard deviations higher on the test was the one they rated 0.56 lower; in an experiment with generative AI available, self-ratings rose more than actual improvement could explain. Viewing time, platform activity, and models predicting a pass mostly measure how much was done, not learning measured separately. This site's traffic statistics are aggregate, and none of its signals can measure whether readers learned.