Self-selection of peers and performance
Last registered on March 19, 2020


Trial Information
General Information
Self-selection of peers and performance
Initial registration date
March 18, 2020
Last updated
March 19, 2020 12:08 PM EDT
Primary Investigator
Other Primary Investigator(s)
PI Affiliation
PI Affiliation
Additional Trial Information
Start date
End date
Secondary IDs
In many natural environments, carefully chosen peers influence individual behavior. Using a framed field experiment at secondary schools, we examine how self-selected peers affect performance in contrast to randomly assigned ones. We find that self-selection improves performance by approximately 16-19% of a standard deviation relative to randomly assigned peers. Our results document peer effects in multiple characteristics and show that self-selection changes these characteristics. However, a decomposition reveals that variations in the peer composition contribute only little to the estimated average treatment effects. Rather, we find that self-selection has a direct effect on performance.
External Link(s)
Registration Citation
Kiessling, Lukas, Jonas Radbruch and Sebastian Schaube. 2020. "Self-selection of peers and performance." AEA RCT Registry. March 19.
Experimental Details
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Percentage point improvments between the first run (alone) and second run (with a peer).
Primary Outcomes (explanation)
We use percentage point improvements as outcome and therefore base our comparisons on the performance in the first run. This takes into account the notion that slower students (i.e., those with a slower time in the first run) can improve more easily by the same absolute value compared with faster students, as it is physically more difficult for the latter.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
In order to study the effects of self-selection, we conducted a framed field experiment with over 600 students (aged 12 to 16) in physical education classes of German secondary schools. Students took part in two running tasks (suicide runs) – first alone, then with a peer – and filled out a survey in between that elicited preferences for peers, personal characteristics, and the social network within each class. Our treatments exogenously varied the peer assignment in the second run using three different peer assignment rules. We implemented a random matching of pairs (Random) as well as two matching rules that used elicited preferences to implement two notions of self-selection: first, the classroom environment enabled students to state preferences for known peers (name-based preferences); and second, using a running task yielded direct measures of performance and thus could be used to select peers based on their relative performance in the first run (performance-based preferences). Using these two sets of preferences, we implemented two treatments with self-selection of peers by matching students based on either their name-based preferences (Name) or preferences over relative performance (Performance).
Experimental Design Details
Randomization Method
We randomized classes into treatments within schools and grades.
Randomization Unit
We randomized classes into treatments within schools and grades.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
39 classes in 3 schools
Sample size: planned number of observations
627 students
Sample size (or number of clusters) by treatment arms
221 in Random, 213 Name, 193 in Performance
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers