This paper develops a machine-learning method that allows researchers to estimate heterogeneous treatment effects with panel data in a setting with many covariates. Our method, which we name the dynamic causal forest (DCF) method, extends the causal-forest method of Wager and Athey (2018) by...

It is a commonly held view that democracy is better at safeguarding environment while autocracy is predatory in nature, and is thus insensitive towards environment. However, others argue that democracy leads to environmental degradation. We revisit this contentious relationship between regime...