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Learning More from Field Experiments

Paper Session

Saturday, Jan. 8, 2022 3:45 PM - 5:45 PM (EST)

Hosted By: Econometric Society
  • Chair: Roland Rathelot, University of Warwick

RCTs to Scale: Comprehensive Evidence from Two Nudge Units

Stefano DellaVigna
,
University of California-Berkeley
Elizabeth Linos
,
University of California-Berkeley

Abstract

Nudge interventions have quickly expanded from academic studies to larger implementation in so-called Nudge Units in governments. This provides an opportunity to compare interventions in research studies, versus at scale. We assemble a unique data set of 126 RCTs covering 23 million individuals, including all trials run by two of the largest Nudge Units in the United States. We compare these trials to a sample of nudge trials in academic journals from two recent meta-analyses. In the Academic Journals papers, the average impact of a nudge is very large—an 8.7 percentage point take-up effect, which is a 33.5% increase over the average control. In the Nudge Units sample, the average impact is still sizable and highly statistically significant, but smaller at 1.4 percentage points, an 8.1% increase. We document three dimensions which can account for the difference between these two estimates: (i) statistical power of the trials; (ii) characteristics of the interventions, such as topic area and behavioral channel; and (iii) selective publication. A meta-analysis model incorporating these dimensions indicates that selective publication in the Academic Journals sample, exacerbated by low statistical power, explains about 70 percent of the difference in effect sizes in the two samples. Different nudge characteristics account for most of the residual difference.

Anticipation and Consumption

Neil Thakral
,
Brown University
Linh Tô
,
Boston University

Abstract

Cash transfer payments are an increasingly widespread policy tool in developed and developing countries, used for both short-term and long-term objectives. We study the design of these policies by examining how the time horizon over which households anticipate receiving transfer payments affects consumption and savings. Using Nielsen Consumer Panel data, we estimate higher marginal propensities to spend for US households scheduled to receive the 2008 Economic Stimulus Payments sooner. Analyzing data from randomized experiments in Kenya and Malawi, we document higher savings among households scheduled to wait longer before receiving lump-sum transfers. We discuss implications of our results through a model of mental accounting.

How Biased Are Observational Methods in Practice? Accumulating Evidence Using Randomised Controlled Trials with Imperfect Compliance

David Bernard
,
Paris School of Economics
Gharad Bryan
,
London School of Economics
Sylvain Chabe-Ferret
,
Toulouse School of Economics
Jon de Quidt
,
Stockholm University
Greg Fischer
,
London School of Economics
Jasmin Fliegner
,
University of Manchester
Roland Rathelot
,
University of Warwick

Abstract

Consider a policy maker choosing between programs of unknown impact. She can inform her decision using observational methods, or by running a randomised controlled trial (RCT). The proponents of RCTs would argue that observational approaches suffer from bias of an unknown size and direction, and so is uninformative. Our study treats this as an empirical claim that can be studied. By doing so we hope to increase the value of observational data and studies, as well as better inform the choice to undertake RCTs. We propose a large-scale, standardised, hands-off approach to assessing the performance of observational methods. First, we collect and categorise data from a large number of RCTs in the past 20 years. Second, we implement new methods to understand the size and direction of expected bias in observational studies, and how bias depends on measurable characteristics of programmes and settings. This will allow us to predict in which context observational studies can provide reliable guidance on the impact of policy interventions.

Evaluating Ex Ante Counterfactual Predictions Using Ex Post Causal Inference

Michael Gechter
,
Pennsylvania State University
Cyrus Samii
,
New York University
Rajeev Dehejia
,
New York University
Cristian Pop-Eleches
,
Columbia University

Abstract

We derive a formal, decision-based method for comparing the performance of counterfactual treatment regime predictions using the results from randomized experiments. Our approach allows us to quantify and assess the statistical significance of differential performance for optimal treatment regimes estimated from structural models, extrapolated treatment effects, expert opinion, and other methods. We apply our method to evaluate optimal treatment regimes for conditional cash transfer programs across countries where predictions are generated using data from experimental evaluations in other countries and pre-program data in the country of interest.
JEL Classifications
  • C2 - Single Equation Models; Single Variables
  • C5 - Econometric Modeling