Data sets from Doing Data Science by Cathy O'Neil and Rachel Schutt. I highly recommended picking up a copy for yourself.
On pages 37-38:
This folder contains 31 simulated days of ads shown and clicks recorded on the New York Times home page. Rows represent users, and the variables are: Age, Gender (0 = female, 1 = male), Impressions (number impressions), Clicks (number clicks), and a binary indicator for signed in or not Signed_in. We need to create two new variables: age_group, which contains six levels of Age ("<18", "18-24", "25-34", "35-44", "45-54", "55-64", and "65+"), and CTR or clickthrough-rate, calculated as the number of clicks / the number of impressions.