“An unexplained annual spike in false claims on the EA Forum” by Tobias Häberli

Epistemic status: Very high confidence in the statistical findings. Genuinely confused about the cause. For reasons that will become obvious, I wanted to publish this post on March 31, but unfortunately I could only get it done today. I've been building a classifier to flag potentially misleading content on the EA Forum as part of a side project on epistemics infrastructure. While validating the model, I noticed something I initially assumed was a bug. This is an interim report on that. Summary: Every year, on April 1, the rate of posts containing verifiably untrue claims spikes by roughly 2,200% relative to the annual daily average (p < 0.0001, 8 years of Forum data). 1. The effect is enormous On a typical day, approximately 2 to 4% of Forum posts contain claims that are verifiably false. On April 1, this rises to 57–73%, depending on the year. For context, this is an implausibly large effect by normal social-science standards. I have genuinely never seen anything like it. 2. It repeats every year This is not a one-off event. The pattern recurs in every year of the dataset. 3. "It's only one day" is misleading A natural reaction is that [...] --- Outline: (01:00) 1. The effect is enormous (01:38) 2. It repeats every year (01:57) 3. Its only one day is misleading (02:57) 4. The false posts are high effort (03:21) Possible explanations (03:30) Why this matters (04:48) Proposed interventions --- First published: April 1st, 2026 Source: --- Narrated by TYPE III AUDIO . --- Images from the article: Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts , or another podcast app.