How to Increase Demand for Evidence in Policymaking: Experimental Evidence from 3,500 Elected Officials

Last registered on July 13, 2026
View Trial History

Pre-Trial

Trial Information

General Information

Title
How to Increase Demand for Evidence in Policymaking: Experimental Evidence from 3,500 Elected Officials
RCT ID
AEARCTR-0019143
Initial registration date
July 09, 2026

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
July 13, 2026, 7:59 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country
Switzerland
Region
Country
Germany
Region
Country
United Kingdom of Great Britain and Northern Ireland
Region

Primary Investigator

Name
Adam Zelizer
Affiliation
University of Chicago
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Miguel Pereira
PI Affiliation
London School of Economics and Political Science
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2024-04-01
End date
2025-01-01
Keywords
Electoral, Governance
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Despite the growing availability of policy evidence, politicians seldom use impact evidence. We argue that demand-side constraints explain part of this gap. In a survey of 3,521 local politicians, we document two key constraints on demand for evidence: (1) knowledge about evidence quality and application, and (2) political incentives. However, these obstacles can be partially overcome. We fielded an experiment that provided randomly-selected politicians with a training course on incorporating evidence in policymaking. The training increased statistical literacy and willingness-to-pay for evidence, though political constraints continue to mediate how politicians incorporate evidence.
External Link(s)

Registration Citation

Citation
Pereira, Miguel and Adam Zelizer. 2026. "How to Increase Demand for Evidence in Policymaking: Experimental Evidence from 3,500 Elected Officials." AEA RCT Registry. July 13. https://doi.org/10.1257/rct.19143-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
We fielded an intensive training intervention that provided randomly-selected politicians in Germany, Switzerland and the United Kingdom with a capacity building course on incorporating evidence in policymaking. The course was developed in conjunction with the Joint Research Center of the European Commission. A pre-treatment survey asked about potential obstacles to the incorporation of evidence in policymaking including political and knowledge constraints.
Intervention (Hidden)
Intervention Start Date
2024-04-01
Intervention End Date
2025-01-01

Primary Outcomes

Primary Outcomes (end points)
Survey and behavioral data from participating officials.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We partnered with the Joint Research Center (JRC) of the European Union (EU) to evaluate a program on statistical literacy for policymakers. The JRC is a department of the European Commission responsible for providing independent advice and support to EU policy. In 2023, the JRC commissioned a training program for local elected officials aimed at better connecting scientific knowledge and policymaking. The JRC released the training materials in 2024. We embedded a streamlined version of this training in an RCT with 150 local politicians recruited in three countries: Germany, Switzerland, and the United Kingdom.\footnote

To isolate the effects of attending the JRC training, we implemented a placebo design. Officials were invited to register for ``a series of online training courses on evidence-based policy making and participatory governance for local elected officials.'' When registering, officials could select one of seven training sessions, held on different dates and times. Notably, they could not choose whether they wanted the evidence-based policymaking or participatory governance training; they could only choose a date and time and were not told which session was being held. Five of the sessions were conducted in English and two in German, to accommodate officials in Switzerland and Germany, though they could also register for the English sessions.

After officials registered for a training, we randomly assigned participants to either the JRC training or the placebo training. The placebo training had the same duration (two hours) and centered on how to organize citizens' assemblies and other forms of participatory governance. It did not discuss incorporating policy evidence or expertise. The placebo sessions were conducted at the same dates and times as the JRC trainings, which means we held 14 training sessions in total.
Experimental Design Details
Randomization Method
Done in office by computer.
Randomization Unit
Individual elected official.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
NA
Sample size: planned number of observations
150
Sample size (or number of clusters) by treatment arms
150
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Research Ethics Review Board
IRB Approval Date
2024-03-18
IRB Approval Number
353832
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials