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The Functioning of Self-Governing Sharing Economies.
Initial registration date
June 21, 2019
May 31, 2020 8:10 AM EDT
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University of Groningen
Other Primary Investigator(s)
University of Groningen
Additional Trial Information
New forms of market mechanisms in which participants share products are becoming increasingly popular. In this project, we address the question whether not-for-profit initiatives in sharing economies, where at most informal rules are at play, can sustain in the long-run and to what extent free-riding occurs. The experimental intervention, which we preregister, is part of a larger study in which we collect field data. For the experimental part, a sample of local markets is randomized into a treatment and control group. After baseline field data have been collected, members of the treatment group receive a positive supply shock and we test whether this shock has a transitory or more permanent effect.
This study collects field data on an unregulated sharing economy to observe the extent to which these markets function without regulation. In the field experimental part, which we preregister, a sample of local markets is randomized into a treatment and control group. After baseline data have been collected, members of the treatment group receive a positive supply shock and we test whether this shock has a transitory or more permanent effect.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
The primary outcome variable of our field experimental intervention is the turnover rate of our experimental units compared to the control units.
Primary Outcomes (explanation)
Secondary Outcomes (end points)
The secondary outcome variable of our field experimental intervention is the multiplier effect that our experimental units have on new non-experimental units in the treatment group compared to new control units.
Secondary Outcomes (explanation)
For the field experimental part of this study, we randomize a number of local markets into a treatment and control group. After baseline data have been collected, members of the treatment group immediately receive a positive supply shock while members of the control group receive this shock later in the study (a few weeks before the end).
Experimental Design Details
30 local markets were allocated to the treatment group and 28 to the control. Randomization was stratified based on four-digit postal codes of the local market and the number of observations per local market as reported in the first week of the study. Randomization was done in the office by a computer using Stata-code.
Was the treatment clustered?
Sample size: planned number of clusters
58 local markets.
Sample size: planned number of observations
58 local markets, per local market a time series of 24 observations will be collected.
Sample size (or number of clusters) by treatment arms
28 local markets in the control group, 30 local markets in the treatment group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
Institutional Review Board of the Faculty of Economics and Business, University of Groningen
IRB Approval Date
IRB Approval Number