This paper uses British panel data to investigate single women’s labour supply changes in response to three tax and benefit policy reforms that occurred in the 1990s. These reforms changed individuals’ work incentives and we use them to identify changes in labour supply. We find evidence of...

A growing literature on inference in difference-in-differences (DiD) designs with grouped errors has been pessimistic about obtaining hypothesis tests of the correct size, particularly with few groups. We provide Monte Carlo evidence for three points: (i) it is possible to obtain tests of the...