Eliciting the ambiguity Attitude of Dragon-slayers and Dyke-builders - An Experimental Study

Last registered on September 15, 2023


Trial Information

General Information

Eliciting the ambiguity Attitude of Dragon-slayers and Dyke-builders - An Experimental Study
Initial registration date
September 12, 2023

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 15, 2023, 8:59 AM EDT

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



Primary Investigator

Paderborn University

Other Primary Investigator(s)

PI Affiliation
Paderborn University
PI Affiliation
Oxford Brookes Business School

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
This paper revisits the effect of ambiguity in strategic games first investigated by Kelsey and le Roux (2017). Once again we consider the impact of ambiguity in two strategic settings: the best-shot and weakest-link versions of public goods provision. We use the recent belief elicitation methodology proposed by Baillon et al. (2021) to elicit model-free ambiguity parameters of subjects' beliefs and ambiguity attitudes and investigate whether the type of strategic setting has an impact on decision-makers' ambiguity aversion (both absolute and relative) and their degree of a(mbiguity)-insensitivity.
External Link(s)

Registration Citation

Bopp, Fabian, Eva Klein and Sara le Roux. 2023. "Eliciting the ambiguity Attitude of Dragon-slayers and Dyke-builders - An Experimental Study." AEA RCT Registry. September 15. https://doi.org/10.1257/rct.11781-1.0
Experimental Details


No intervention
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
ambiguity attitudes in best-shot-PGG, weakest-link-PGG, and Ellsberg (aversion index and a-insensitivity index)
Primary Outcomes (explanation)
The outcome will be constructed using the matching probabilities following the procedure of Baillon et al. (2021)

Secondary Outcomes

Secondary Outcomes (end points)
contribution in best-shot-PGG and weakest-link-PGG
Secondary Outcomes (explanation)
We directly elicit the contribution on a scale from 100-150 in steps of 10.

Experimental Design

Experimental Design
The design consists of best-shot-PGG, weakest-link-PGG, and Ellsberg game. Additionally following Baillon et al. (2021) we elicit the matching probabilities. To control for prosocial preferences and for reasoning abilities we use a donation decision and CRT questions
Experimental Design Details
Randomization Method
We randomize the order of PGG variants. This is implemented by a computer.
Randomization Unit
randomization is done on an individual level.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
We plan to observe 400 subjects. (The actual number may depend on the available budget)
Sample size: planned number of observations
We plan to observe 400 subjects. (The actual number may depend on the available budget)
Sample size (or number of clusters) by treatment arms
400 subjects (The actual number may depend on the available budget)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
given a power of 0.9 and 400 subjects, we are able to observe an effect size of 0.15. This i.e. would translate into a change in the calculated parameter for a-insensitivity index from 0.30 to 0.35 points with a standard deviation of 0.45. The assumed values are selected based on Dorobiala and Melkonyan (2023).

Institutional Review Boards (IRBs)

IRB Name
Paderborn University ethical commission
IRB Approval Date
IRB Approval Number


Post Trial Information

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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