Empirical approach
REGRESSIONS
We pre-registered our analysis plan via the Open Science Framework. (Our pre-registration plan can be viewed at Our pre-registered dependent variable is the cumulative number of COVID-19 vaccine first doses administered in each county up through a particular date. We focus only on vaccine recipients who are 12 or older, as children ages 5 to 11 only became eligible after our campaign ended (in early November 2021). An observation in our analysis is a given county on a given date.Let The variable λOur estimation algorithm to incorporate these two-way fixed effects relies on Baum One important assumption underlying our analysis is the stable unit treatment value assumption (SUTVA), which requires that a county’s treatment status does not affect the potential outcomes of other counties. This assumption could be violated, for example, if some people view the ad in a treatment county and then cross county borders into a control county to get the vaccine. If present, this type of violation would lead to our estimates of the ITT effect being understated.In some regressions, we modify 