Polls and the pandemic:estimating the electoral effects of a SARS-CoV-2 outbreak

The novel coronavirus (SARS-CoV-2) and the associated Coronavirus Disease 2019 (COVID-19) pandemic have had far-reaching health, economic, social and political impacts. The latter is the focus of this research note, which proposes using a difference-in-differences approach to estimate the electoral impact of reported SARS-CoV-2 infection rates. The approach is illustrated using data from the 2020 Croatian parliamentary election. The outcomes of interest are the vote shares for the dominant Croatian Democratic Union party, as well as the turnout. The analysis concludes that there is no evidence that reported county-level infection rates affected Croatian Democratic Union support or turnout. However, results using this approach may be affected by the statistical power of the analysis, issues related to causal identification and reliability of infection rate measures. Nonetheless, the difference-in-differences approach can potentially be applied in contexts around the world to estimate the electoral impact of reported SARS-CoV-2 infection rates.