Don’t Jump to Faulty Conclusions: Using the Synthetic Control Method to Evaluate the Effect of a Counterfactual Lockdown in Sweden

Abstract

Several studies based on the Synthetic Control Method (SCM) link the many COVID-19 deaths in Sweden during the spring of 2020 to its decision not to lock down. These studies predominantly rely on a limited pre-intervention period and tend to focus on the very short run neglecting that Swedish health authorities emphasized that their public health strategy was designed for the long run. This paper handles these shortcomings expanding both the pre- and post-intervention period considerably using weekly mortality rates. I find no significant effect of the absence of lockdown on COVID-19 mortality neither in the short or long run. Using the timing of the winter holiday as a proxy for the extent/spread of COVID-19 in societies before lockdown - a variable which is unobservable due to limited testing - I suggest that the effect of lockdowns found in earlier studies using Sweden as a control are likely to be partially driven by unobserved variables rather than policies.