Frictions in Forecasting: Experimental Evidence from Professional Forecasters

Last registered on October 23, 2025
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Pre-Trial

Trial Information

General Information

Title
Frictions in Forecasting: Experimental Evidence from Professional Forecasters
RCT ID
AEARCTR-0017013
Initial registration date
October 20, 2025

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
October 23, 2025, 7:14 AM EDT

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

Locations

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Primary Investigator

Name
Lora Pavlova
Affiliation
ZEW - Leibniz Centre for European Economic Research
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Other Primary Investigator(s)

PI Name
Davud Rostam-Afschar
PI Affiliation
University of Mannheim
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PI Name
Lukas Hack
PI Affiliation
ETH Zurich and University of Mannheim
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Additional Trial Information

Status
In development
Start date
2025-11-03
End date
2027-11-10
Keywords
Behavior, Other
Additional Keywords
Forecasting behavior, Professional forecasters, Expectation formation, Belief updating, Survey data
JEL code(s)
C9, D83, E37
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We study how information about the distribution of peers’ forecasts affects professional forecasters’ own predictions. Using the Finanzmarkttest (FMT) survey of financial market experts, conducted monthly by ZEW Mannheim, we implement an information provision experiment. Participants provide quarterly GDP growth forecasts for Germany. A randomly selected subset (treatment group) receives information about the actual share of forecasters whose previous forecast was lower than their own. This allows us to causally identify whether forecasters adjust their expectations in response to information about the forecast distribution, revealing motives in professional forecasting that go beyond pure forecast accuracy considerations.
External Link(s)

Registration Citation

Citation
Hack, Lukas, Lora Pavlova and Davud Rostam-Afschar. 2025. "Frictions in Forecasting: Experimental Evidence from Professional Forecasters." AEA RCT Registry. October 23. https://doi.org/10.1257/rct.17013-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
In our experiment, we provide a random subset of all FMT professional forecasters with information about the distribution of survey forecasts. This helps us to causally identify whether the ``forecasts of others'' matter for the own prediction of a given forecaster.
Intervention Start Date
2025-11-03
Intervention End Date
2025-11-10

Primary Outcomes

Primary Outcomes (end points)
quarter-on-quarter real GDP growth forecasts, belief about the consensus, belief about the consensus gap, belief about the relative position in the distribution, treatment intensity, forecast revision
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Responses in subsequent FMT waves (forecast persistence), Self-reported forecast methodology (model-based vs judgment-based), Comparison to expert predictions
Secondary Outcomes (explanation)
The comparison to expert prediction refers to a complementary survey among experts on their expectations about the outcomes of the trial via the Social Science Prediction Platform.

Experimental Design

Experimental Design
Treatment group: Receives feedback on the true share of participants whose prior forecast (from an earlier wave) was lower than their own prior forecasts (“distribution information”). Control group and treatment group: Receives their own previous forecast and the consensus (average) forecast, but no information about the distribution. Both groups report priors and posteriors about GDP growth and beliefs about the consensus forecast.
Experimental Design Details
Not available
Randomization Method
Random assignment of participants to treatment and control groups within the November 2025 FMT survey wave. Randomization will be performed in survey software prior to fielding and will not be visible to participants.
Randomization Unit
Individual forecaster
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
Expected participants: ~120–150
Sample size: planned number of observations
Expected participants: ~120–150
Sample size (or number of clusters) by treatment arms
Expected participants per treatment arm: ~60-75
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
ZEW Ethics Committee
IRB Approval Date
2025-10-13
IRB Approval Number
ZEW-EC-2025-006
Analysis Plan

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