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...

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...

We use a rigorous three-stage many-analysts design to assess how different researcher decisions—specifically data cleaning, research design, and the interpretation of a policy question—affect the variation in estimated treatment effects. A total of 146 research teams each completed the same...

The UK Universal Credit (UC) welfare reform simplified the benefits system whilst strongly incentivising a return to sustainable employment. Exploiting a staggered roll-out, we estimate the differential effect of entering unemployment under UC versus the former system on mental health. Groups...

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 substantial body of research on the UK's National Minimum Wage (NMW) has concluded that the the NMW has not had a detrimental effect on employment. This research has directly influenced, through the Low Pay Commission, the conduct of policy, including the subsequent introduction of the...

Increasing the labour market participation of single parents, whether to boost incomes or reduce welfare spending, is a major policy objectives in a number of countries. This paper presents causal evidence on the impact of work search requirements on single parents' transitions into work and...

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...

Time-limited in-work credits are cheaper, and more targeted, than conventional in-work credits, but are thought to have small to zero long-term impacts. We study two time-limited in-work credits introduced in the mid-2000s in the UK and find they reduced welfare participation and increased...

Despite the introduction of childcare subsidies in many countries, the cost of childcare is still thought to hinder parental employment. Many governments are considering increasing the generosity of their childcare subsidies, but the a priori effect of such a policy is ambiguous and little is...