Pandemic Politics: Timing State-Level Social Distancing Responses to COVID-19

Christopher Adolph; Kenya Amano; Bree Bang-Jensen; Nancy Fullman; John Wilkerson

We estimate an event history model to predict the timing of implementing social distancing directives across U.S. states from 26 February 2020 to 23 March 2020. 3 We model the likelihood that a state will implement each social distancing policy as a function of time (measured in days) with a pooled, stratified Cox proportional hazards model, often referred to as the Wei-Lin-Weissfeld marginal model. (22) In our application, this approach allows us to examine the common factors affecting implementation of social distancing across states by 1) pooling the five social distancing measures shown in Figure 1 in a single model, (2) stratifying baseline hazards across the five policy types to allow for varying underlying tendencies to adopt some policies more quickly than others, and (3) clustering standard errors by state.