Scott Alexander criticizes a study on e-cigarette effectiveness for quitting smoking, explaining potential sampling bias that could skew the results. Longer summary

Scott Alexander critiques a study claiming e-cigarette users are no more likely to quit smoking tobacco after a year than non-users. He explains why he's skeptical of the study's methodology, using a hypothetical world analogy to illustrate potential sampling bias. Scott suggests that the study might be capturing more unsuccessful e-cigarette users due to their longer period of dual use, skewing the results. He ends with a brief, unrelated mention of his addiction-medicine teacher appearing on Fox News to discuss marijuana. Shorter summary

Scott Alexander examines evidence on marijuana legalization's effects on usage, health, and drug war costs, finding uncertainties too large for firm conclusions but suggesting traffic accidents may be the key factor. Longer summary

Scott Alexander examines the evidence around marijuana legalization, looking at its effects on usage rates, health impacts, and costs of the drug war. He finds that decriminalization and medical marijuana don't seem to increase youth usage much, but full legalization might increase adult use by 25-50%. Health effects are unclear but may include IQ declines and slightly increased psychosis risk. The costs of the drug war are significant in terms of arrests and spending, but relatively few people are in prison solely for marijuana. Scott attempts a utilitarian analysis comparing costs and benefits of legalization, but finds the uncertainties too large to draw firm conclusions. He suggests the most important factor may be how legalization affects traffic accidents. Shorter summary