An Introduction to Difference-in-Difference Analysis
Here, we compute the average rating for the treatment and control group both before and after the Q&A launch based on the GoodAma dataframe. The treatment dummy, goodr = 1 indicates the treatment group (Goodreads), and otherwise the control group (Amazon). The time dummy, qa = 1 indicates the after period and 0 for the before period. Difference in …
