NEW UPDATE: Completed trials may now upload and register supplementary documents (e.g. null results reports, populated pre-analysis plans, or post-trial results reports) in the Post Trial section under Reports, Papers, & Other Materials.
Initial registration date
November 18, 2019
November 20, 2019 2:58 PM EST
This section is unavailable to the public. Use the button below
to request access to this information.
University of Cologne
Other Primary Investigator(s)
University of Cologne
Additional Trial Information
In this study, we investigate the presence and stability of dynamically inconsistent time preferences across contexts with and without interpersonal trade-oﬀs. In a longitudinal experiment, across six different treatments, subjects make a series of intertemporal allocation decisions of real-eﬀort tasks between themselves and another person.
In a lab experiment, we investigate the presence and stability of dynamically inconsistent time preferences across contexts with and without interpersonal trade-oﬀs.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Our primary variable of interest is whether generosity (as measured by the number of tasks allocated to another person) differ between the different points in time in which choices are made and consequences of these choices are realized (see below).
Primary Outcomes (explanation)
This study is a replication of the experiment reported in our working paper (Koelle and Wenner, 2019). In the analysis of the new data, we will use exactly the same analysis for the reduced form effects as well as the structural estimates. We will also employ the same exclusion criteria for choices as in our earlier study. Under "Docs & Materials" we have uploaded the most recent version of our working paper and the corresponding online appendix in which we explain all our estimation procedures and exclusion criteria in detail.
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
This study is a replication of our study "Time-Inconsistent Generosity: Present Bias across Individual and Social Contexts" (Working Paper, 2019). We conduct exactly the same experiment as the one we did in 2017, except for a different sample size which we determine by means of a power calculation (see below). What follows is the description of the experiment as it appears in the working paper:
We conduct a three-week longitudinal experiment in which participants are asked to make intertemporal allocation decisions of units of effort (i.e., negative leisure consumption) for varying prices using a convex budget set approach. Allocation decisions are made at two points in time - an initial allocation in week 1, and a subsequent allocation in week 2 - while effort needs to be exerted in week 2 or in week 3. Each subject makes choices in two types of allocation decisions. In the first, subjects face intertemporal trade-offs in a social context in which they allocate tasks between themselves and another person. In contrast to choices in standard (static) dictator games, we systematically vary the timing of when the consequences for the decision maker and the consequences for recipient realize; either both immediately, both delayed, or one delayed and the other immediately. In the second type of allocation decisions, subjects face intertemporal trade-offs that either only affect themselves or only affect another person, i.e., choices in which there is no conflict between own and others' consumption. In total, subects make decisions in six different treatments, and the order in which these decisions are displayed to subjects is randomized at te individual level.
Experimental Design Details
Randomization is done by the computer.
Was the treatment clustered?
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
1,716 decisions per treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We determine our sample size based on the results of our previous study. In particular, we calculate the sample size required to obtain our main effect of a reduced degree of generosity when consequences are immediate with a power of 80% at a significance level of 5%.
Our power calculation is based on the "diff-in-diff" reported in the bottom right cell in Table 3 of our working paper. This "diff-in-diff" is calculated as the difference between the difference in tasks allocated to oneself for the week 2 work date (decision in week 1 minus decision in week 2) minus the difference in tasks allocated to oneself for the week 3 work date (decision in week 1 minus decision in week 2). This effect is given by 1.80 tasks (s.d. 6.066).
Based on this, we calculate an effect size of 0.297. Using a t-test for paired samples, we calculate that we require a sample size of n=92 to be able to reject the null hypothesis with a power of 80% at a significance level of 5% given this effect size.
In our previous study, we find that of the 110 participants who complete week 1 of the experiment, 104 return for week 2. Of these 104 participants, 33 are excluded from the analysis because their behavior shows no response to changes in the relative price of giving (in almost all cases, this is because participants are fully selfish and never allocate any tasks to themselves). Using these rates as our best estimate for the new study, we expect to need 92*(110/71) =~ 143 participants.
Supporting Documents and Materials
There are documents in this trial unavailable to the public. Use the button below to request access to this information.
Koelle and Wenner (2019) - Online Appendix
Working Paper (Online Appendix) of the study which we seek to replicate here.
Koelle & Wenner (2019)
Working Paper of the study which we seek to replicate here.
Koelle & Wenner (2019)
November 17, 2019
INSTITUTIONAL REVIEW BOARDS (IRBs)