Authors: Sam Sims, Jake Anders, and Laura Zieger

June 2021

This report focuses on whether one particular non-experimental method can reproduce the results from experimental evaluations: the comparative interrupted time series (CITS) design. The basic idea is to compare the way in which outcomes in the treatment group deviate from trend after an intervention is introduced, relative to the way in which outcomes in the control group deviate from trend at the same point in time. Under certain assumptions, the difference between these deviations can be interpreted as the effect of the intervention.