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 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