Differences-in-Differences is a popular quasi-experimental methodology used to estimate causal effects from longitudinal observational data. We evaluate the impact of a city level intervention using differences-in-differences under a simple pre-post and control-treatment environment. The animation illustrates how to obtain the differences-in-differences estimate using a regression model.

Details on animation tool:
   • Math and Animation Tool Tutorial  

References and other Diff-in-Diff resources:
   • An intuitive introduction to Differen...  
   • Identification, Part 4: Differences-i...  
   • Difference in Differences Pt 1  
   • The Common Trends Assumption: Causal ...  
   • Graphical Analysis of the Common Tren...