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Morals in multi-unit markets
Last registered on June 29, 2020


Trial Information
General Information
Morals in multi-unit markets
Initial registration date
September 15, 2019
Last updated
June 29, 2020 5:02 AM EDT

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Primary Investigator
Other Primary Investigator(s)
PI Affiliation
University of Amsterdam
PI Affiliation
University of Amsterdam
Additional Trial Information
In development
Start date
End date
Secondary IDs
The result that markets erode morals (Falk & Szech, 2013) has recently been challenged (for instance by Bartling et al., 2019). Recent experiments on norm erosion restrict market participants to trade at most one unit. This choice might limit the extent to which market forces facilitate selfish behavior and outcomes. In this project, we study markets with multi-unit trading. We establish whether the moral concerns of traders are reflected in market outcomes to the degree that is theoretically predicted and whether there is norm erosion in markets by comparing valuations of a charity donation in individual decision-making to the valuations in markets with single and multi-unit trading.
External Link(s)
Registration Citation
Offerman, Theo, Giorgia Romagnoli and Andreas Ziegler. 2020. "Morals in multi-unit markets." AEA RCT Registry. June 29. https://doi.org/10.1257/rct.4603-1.1.
Sponsors & Partners

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Experimental Details
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
There are two main outcome dimensions in this experiment:

• Individual valuations of a charity donation, directly elicited from participants in individual choices or inferred from bid and ask prices and accepted offers in markets. In these markets, trading produces an externality by reducing donations to a charity.

• Traded quantities in the markets.

Primary Outcomes (explanation)
For a detailed explanation of out outcome variables, see the analysis plan.
Secondary Outcomes
Secondary Outcomes (end points)
We compare social norms about appropriative behavior in- and outside of markets and subjects' beliefs about the median valuation of the donation between treatments.
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We run four treatments: IDM, SINGLE, MULTI and FULL. SINGLE, MULTI and FULL are three types of markets, where the total number of tradeable units change (5 in SINGLE, 15 in MULTI and FULL), as well as the maximum number of tradeable units per trader (1 in SINGLE, 3 in MULTI and 15 in FULL).
Experimental Design Details
Not available
Randomization Method
Computerized randomization.
Randomization Unit
Subjects are first randomly allocated to one of the market treatments or the individual-decision making (computerized). For market treatments, subjects are then randomly allocated to a group (computerized), and subsequently each group is assigned a treatment.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
10 groups with 10 subjects each per market treatment. No clustering in individual decision making.
Sample size: planned number of observations
380 subjects
Sample size (or number of clusters) by treatment arms
For the three market treatments (SINGLE, MULTI, FULL), we aim for 10 groups with 10 subjects each (3*10*10=300 subjects). For IDM, we aim for 80 subjects (for this treatment, each subject provides one independent observation). If we run out of subjects before we reach these targets, we will collect as many observations as we can.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Economics & Business Ethics Committee (University of Amsterdam)
IRB Approval Date
IRB Approval Number
EC 20190617030625
Analysis Plan

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