The Principal Causal Impact

The Principal Causal Impact measures the effect of an intervention or change on a specific outcome by comparing what actually happened to what would have likely occurred without the intervention. It uses a model built from historical data to estimate the counterfactual—what the outcome would have been without the change—and then assesses the difference between this estimate and the observed result. This approach helps determine whether and how much an intervention influenced the outcome, providing a clearer understanding of cause-and-effect relationships.