Knowledge of treatment effect heterogeneity or "essential heterogeneity" plays an important role in our understanding of how programs work and in the design of systems to allocate them among the eligible. This paper provides a relatively non-technical survey of the current state of the treatment...

Quantitative school performance measures (QPMs) are playing an ever larger role in education systems on both sides of the Atlantic. In this paper we outline the rationale for the use of such measures in education, review the literature relating to several important problems associated with their...

We study the job training provided under the US Workforce Investment Act (WIA) to adults and dislocated workers in two states. Our substantive contributions center on impacts estimated non-experimentally using administrative data. These impacts compare WIA participants who do and do not receive...

The "common effect" model in program evaluation assumes that all treated individuals have the same impact from a program. Our paper contributes to the recent literature that tests and goes beyond the common effect model by investigating impact heterogeneity using data from the experimental...

This paper evaluates the UK New Deal for Lone Parents (NDLP) program, which aims to return lone parents to work. Using rich administrative data on benefit receipt histories and a "selection on observed variables" identification strategy, we find that the program modestly reduces benefit receipt...

We provide simple tests for selection on unobserved variables in the Vytlacil-Imbens-Angrist framework for Local Average Treatment Effects. The tests allow researchers not only to test for selection on either or both of the treated and untreated outcomes, but also to assess the magnitude of the...

Estimation, inference and interpretation of the causal effects of programs and policies have all advanced dramatically over the past 25 years. We highlight three particularly important intellectual trends: an improved appreciation of the substantive importance of heterogeneous responses and of...

We present experimental evidence on the effects of four U.S. reemployment programs for youth Unemployment Insurance (UI) recipients during the Great Recession. The three programs that emphasized monitoring and service referrals reduced UI receipt but had minimal effects on employment and...

We document substantial variation in the effects of a highly-effective literacy program in northern Uganda. The program increases test scores by 1.4 SDs on average, but standard statistical bounds show that the impact standard deviation exceeds 1.0 SD. This implies that the variation in effects...

How well do program participants assess program performance ex-post? In this paper we compare participant evaluations based on survey responses to econometric impact estimates obtained using data from the experimental evaluation of the U.S. Job Training Partnership Act. We have two main...