Scott demonstrates that US crime rates are at historic lows using multiple data sources, then debunks the theories that this is due to reporting bias or improved medical care, before briefly discussing possible explanations for the decline. Longer summary

Scott presents evidence that US crime rates, particularly murder rates, are at or near historic lows, then systematically debunks two common objections: that the decline is due to underreporting bias, and that it's an artifact of improved medical care saving would-be murder victims. He shows that multiple independent data sources (including victim surveys and consistently-reported crimes like car theft) confirm the decline, and that while medical care has improved, gun injuries have become more severe at roughly the same rate, canceling out the effect. The post concludes by listing various theories for why crime has declined and questioning why public perception doesn't match the data. Shorter summary

Scott Alexander explores the potential link between falling testosterone levels and declining crime rates, finding the hypothesis intriguing but ultimately insufficient to explain observed crime trends. Longer summary

Scott Alexander explores the hypothesis that falling testosterone levels might be related to the secular decline in crime. He examines studies showing a significant drop in testosterone levels in American men from 1987 to 2004, and research linking higher testosterone to violent crime. However, he identifies several problems with this hypothesis, including timing discrepancies between testosterone decline and crime reduction, contradictory evidence, and the fact that crime is dropping in women at the same rate as in men. While intrigued by the potential connection, Scott concludes that the hypothesis doesn't fully explain the observed crime trends. He suggests further research, including studies comparing testosterone levels in violent criminals to the general population and proposing an examination of digit ratios in historical skeletal remains to track testosterone levels over time. Shorter summary

Scott Alexander questions the plausibility of multifactorial explanations for trends, using the US crime rate decline as an example, and seeks literature on comparing single-factor vs multi-factor explanations. Longer summary

Scott Alexander discusses the plausibility of multifactorial trends, using the decline in US crime rates as an example. He presents two perspectives: one arguing that complex phenomena like crime are likely caused by many small factors, and another suggesting that simultaneous changes in multiple factors is improbable. Scott leans towards the second perspective, questioning the likelihood of ten different factors each accounting for about 10% of the crime decline. He asks if there are ways to calculate the relative likelihood of single-factor versus multi-factor explanations, noting that he feels he's missing an existing body of literature on this topic. Shorter summary

Scott Alexander explores biological factors like lead exposure, omega-6 fatty acids, and lithium levels as potential explanations for historical crime rate trends, particularly the possible increase from 1850 to 1980. Longer summary

Scott Alexander discusses potential biological explanations for historical trends in crime rates. He provisionally accepts that crime may have increased from 1850 to 1980, contrary to his previous belief. He then explores three biological factors that could explain this trend: lead exposure, omega-6 fatty acid consumption, and lithium levels in water. Scott argues that increased lead exposure from industrialization, a dramatic rise in omega-6 fatty acid consumption, and decreased lithium in water due to modern purification methods could all contribute to higher crime rates. He presents evidence linking these factors to aggression and crime, including studies on dietary supplements reducing violence in various populations. Shorter summary

Scott Alexander debunks claims of effectiveness for Vancouver's 'Don't Be That Guy' anti-rape campaign, arguing that the reported crime reduction is likely due to normal statistical fluctuations rather than the campaign's impact. Longer summary

Scott Alexander critiques claims that the 'Don't Be That Guy' anti-rape campaign in Vancouver reduced sexual assault rates by 10%. He argues that such small changes in crime rates are common and don't necessarily indicate causation. He examines crime statistics from Vancouver and Edmonton, where the campaign originated, showing that similar fluctuations occur in various crime categories and across different years. Scott suggests that the apparent success of the campaign may be due to selective reporting and misinterpretation of statistics. He concludes by proposing that such campaigns might be more about signaling group membership than actually reducing crime. Shorter summary