In our professional services firm, we want to understand whether workers that are allowed to decorate their offices become productivity as a result.initially, every office was uniform in decorating style.However, we randomly selected a fraction of workers(treatment group) and allowed them to decorate their offices.The rest had to put up with uniform style(control group). We measured the productivity of everybody both before and after.

a) Write down the population model that will allow you to obtain a differences-in-differences estimator.

b) In your population model, what is the expected productivity of workers in the treatment group before they were allowed to decorate their offices?

Month January February Sales FMA3 FMAS FWMA 20 21 March 15 18.67 April May 14 16.67 16.3 13 14.00 16.60 14.5 June 16 14.33 15.80 14.6 July 17 15.33 15.00 15.6 August September October November December 18 17.00 15.60 16.8 20 18.33 16.80 18.4 20 19.33 18.20 19.3 21 20.33 19.20 20.2 23 21.33 20.40 21.5 21.00 20.60 20.7 January February 19 18 20.00 20.20 19.6 March 21 19.33 20.40 19.9 April May 17 18.67 19.60 18.6 23 20.33 19.60 20.3 June 22 20.67 20.20 21.2 July 16 20.33 19.80 19.3 August 20 19.33 19.60 19.5 September October 20 18.67 20.20 19.4 18 19.33 19.20 18.8 November 17 18.33 18.20 18.2 December January 19 18.00 18.80 18.3