Scott Alexander argues that selection bias, while a concern, is not a valid reason to automatically reject amateur online surveys, as professional studies also face similar limitations. Longer summary

Scott Alexander discusses the issue of selection bias in amateur online surveys, arguing that it's not a valid reason to dismiss their results outright. He points out that professional scientific studies also suffer from selection bias, often using unrepresentative samples like psychology students. The post explains that while selection bias is problematic for polls or census-like studies aiming to determine population-wide statistics, it's less of an issue for correlation studies. Scott argues that the key is to consider the mechanism being studied and how it might generalize, rather than dismissing studies based solely on their sample selection method. Shorter summary

Scott Alexander examines seven cognitive traps that lead doctors to believe they're above-average, potentially applying to other client-choice professions. Longer summary

Scott Alexander explores why doctors often believe they're above-average practitioners. He presents seven cognitive traps that contribute to this belief: 1) Doctors mainly see patients who left worse doctors, 2) Patient retention creates a positively biased sample, 3) Patient departures are often unnoticed, 4) Long-term patients are usually success stories, 5) Doctors are aware of others' mistakes but not their own, 6) Successes are attributed to skill while failures are attributed to circumstances, and 7) Doctors excel at metrics they personally value. Scott suggests these biases might apply to other professions where clients choose their service providers. Shorter summary

Scott Alexander debunks a study claiming Victorians were smarter than modern people, showing it's based on flawed data comparison and ignores crucial factors like selection bias and demographics. Longer summary

Scott Alexander critiques a study claiming Victorians were more intelligent than modern people based on reaction time measurements. He argues the study's conclusion is flawed due to significant selection bias in the Victorian data, which primarily came from wealthy, educated individuals. The modern data, in contrast, was more representative of the general population. Scott points out that the difference in reaction times can be explained by sampling from the top 20% of Victorian society versus a broader modern sample. He also highlights how the study ignores important factors like race and regional variations in IQ, which could further account for the observed differences. Scott concludes by urging readers not to cite this study as evidence for declining intelligence or civilization. Shorter summary

Scott Alexander explores how selection bias might create the stereotype of angry, vocal atheists, and speculates on how this concept might apply to other groups. Longer summary

This post discusses how selection bias may contribute to the stereotype of atheists as loud and angry. Scott argues that while religious people are visible in many contexts, atheists are typically only noticed when criticizing religion or advocating for atheist causes. This creates a false impression that atheists are obsessed with attacking religion. The post suggests that most atheists rarely discuss their lack of belief, but these individuals don't get attention as atheists. Scott then extends this concept to other groups, speculating that similar selection biases might contribute to stereotypes about Muslims, Christians in secular areas, and even ethnic groups. Shorter summary