<p> 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.</p><p> 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.</p><p> 
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 &lt; 0.0001, 8 years of Forum data).
<br> </p><p><strong> 1. The effect is enormous</strong></p><p> 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.</p><p><strong> 2. It repeats every year</strong></p><p> This is not a one-off event. The pattern recurs in every year of the dataset.</p><p><strong> 3. "It's only one day" is misleading</strong></p><p> A natural reaction is that [...]</p></br></p> <p>---</p><p><strong>Outline:</strong></p><p>(01:00) 1. The effect is enormous</p><p>(01:38) 2. It repeats every year</p><p>(01:57) 3. Its only one day is misleading</p><p>(02:57) 4. The false posts are high effort</p><p>(03:21) Possible explanations</p><p>(03:30) Why this matters</p><p>(04:48) Proposed interventions</p> <p>---</p> <p><b>First published:</b><br/> April 1st, 2026 </p> <p><b>Source:</b><br/> <a href="https://forum.effectivealtruism.org/posts/EAokRDmQTjCAWgGdq/an-unexplained-annual-spike-in-false-claims-on-the-ea-forum?utm_source=TYPE_III_AUDIO&utm_medium=Podcast&utm_content=Source+URL+in+episode+description&utm_campaign=ai_narration" rel="noopener noreferrer" target="_blank">https://forum.effectivealtruism.org/posts/EAokRDmQTjCAWgGdq/an-unexplained-annual-spike-in-false-claims-on-the-ea-forum</a> </p> <p>---</p> <p>Narrated by <a href="https://type3.audio/?utm_source=TYPE_III_AUDIO&utm_medium=Podcast&utm_content=Narrated+by+TYPE+III+AUDIO&utm_term=ea_forum&utm_campaign=ai_narration" rel="noopener noreferrer" target="_blank">TYPE III AUDIO</a>.</p> <p>---</p><div style="max-width: 100%";><p><strong>Images from the article:</strong></p><a href="https://res.cloudinary.com/cea/image/upload/f_auto,q_auto/v1/mirroredImages/EAokRDmQTjCAWgGdq/en3rvkx5t2yp9uz63fej" target="_blank"><img src="https://res.cloudinary.com/cea/image/upload/f_auto,q_auto/v1/mirroredImages/EAokRDmQTjCAWgGdq/en3rvkx5t2yp9uz63fej" alt="Line graph titled "Share of EA Forum posts containing demonstrably false claims (average across years)."" style="max-width: 100%;" /></a><hr style="margin-top: 24px; margin-bottom: 24px;" /><a href="https://res.cloudinary.com/cea/image/upload/f_auto,q_auto/v1/mirroredImages/EAokRDmQTjCAWgGdq/ftop0cixiq6jdyfreoqj" target="_blank"><img src="https://res.cloudinary.com/cea/image/upload/f_auto,q_auto/v1/mirroredImages/EAokRDmQTjCAWgGdq/ftop0cixiq6jdyfreoqj" alt="Line graph showing "Share of EA Forum posts containing demonstrably false claims by year."" style="max-width: 100%;" /></a><p><em>Apple Podcasts and Spotify do not show images in the episode description. Try <a href="https://pocketcasts.com/" target="_blank" rel="noreferrer">Pocket Casts</a>, or another podcast app.</em></p></div>