We document four facts about the worldwide COVID-19 pandemic that are relevant for those studying the impact of nonpharmaceutical interventions (NPIs) on COVID-19 transmission. First, across all countries and U.S. states that we study, the growth rates of daily deaths from COVID-19 fell from a...

There have been more than 500,000 opioid overdose deaths since 2000. To analyze the opioid epidemic, we construct a model where individuals, with and without pain, choose whether to misuse opioids knowing the probabilities of addiction and dying. These odds are functions of opioid use. Markov...

We construct a unified objective measure of health status: the frailty index, defined as the cumulative sum of all adverse health indicators observed for an individual. First, we show that the frailty index has several advantages over self-reported health status, particularly when studying...

There have been more than 500,000 opioid overdose deaths since 2000. To analyze the opioid epidemic, a model is constructed where individuals choose whether to use opioids recreationally, knowing the probabilities of addiction and dying. These odds are functions of recreational opioid usage....