Medical experts have argued forcefully that using cigarettes harms health, prompting the adoption of myriad anti-smoking policies. The association between smoking and mortality may, however, be driven by unobserved factors, making it difficult to discern the underlying long-term causal...

Medical experts have argued forcefully that using cigarettes harms health, prompting the adoption of myriad anti-smoking policies. The association between smoking and mortality may, however, be influenced by unobserved factors, making it difficult to discern the underlying long-term causal...