Moral Luck

Last registered on September 20, 2021


Trial Information

General Information

Moral Luck
Initial registration date
September 20, 2021

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
September 20, 2021, 6:42 PM EDT

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



Primary Investigator


Other Primary Investigator(s)

PI Affiliation
PI Affiliation

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
We run online experiments using a nationally representative US sample to investigate the existence and nature of moral luck and explore potential mechanisms. Subjects are "spectators," who are informed about choices and random outcomes of "active players," and can spend money to deduct money from the active players (punish).
External Link(s)

Registration Citation

Falk, Armin, Sven Heuser and David Huffman. 2021. "Moral Luck." AEA RCT Registry. September 20.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Punishment amounts chosen by spectators (in dollars)
Primary Outcomes (explanation)
See pre-analysis plan

Secondary Outcomes

Secondary Outcomes (end points)
Qualitative assessments of the active player's character and active player's choice
Beliefs about the active player's value of the life of a mouse
Self-reported emotions about the active player
Secondary Outcomes (explanation)
See pre-analysis plan

Experimental Design

Experimental Design
The study uses a spectator design to study moral luck. The basic structure of the experiment is as follows:

As groundwork, we ran experiments in the Bonn Econlab with “active payers” who had to choose between an immoral and a moral lottery. The moral lottery gave no additional money and a lab mouse was killed with 30% and rescued with 70%. The immoral lottery gave additional $6 (5Euro), but a mouse was killed with 70% and rescued with 30%. The choice was not hypothetical, but had real consequences.

In this study, spectators can punish these “active players” based on both their decision and the outcome for the mouse. Moreover, we elicit further measures and run two further treatments to shed light on the mechanism behind moral luck and understand potential ways to de-bias moral luck.
Experimental Design Details
See pre-analysis plan
Randomization Method
Randomization is done by computer.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
An individual spectator is a cluster. Each spectator makes 4 punishment decisions, so there are 4 observations of the main dependent variable per cluster. For more details see pre-analysis plan.
Sample size: planned number of observations
Our target is to recruit 4.400 spectators
Sample size (or number of clusters) by treatment arms
Our target recruitment numbers by treatment are: 2,000 spectators for Treatment Main, 1.200 spectators for each of two other treatments.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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Institutional Review Boards (IRBs)

IRB Name
IRB board of the department of economics, University of Bonn
IRB Approval Date
IRB Approval Number
Analysis Plan

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Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials