Gift Exchange at Work

Last registered on February 26, 2021


Trial Information

General Information

Gift Exchange at Work
Initial registration date
November 23, 2014

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
November 23, 2014, 1:20 AM EST

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

Last updated
February 26, 2021, 10:34 AM EST

Last updated is the most recent time when changes to the trial's registration were published.



Primary Investigator

Harvard University

Other Primary Investigator(s)

PI Affiliation
University of California, Berkeley
PI Affiliation
University of California, Berkeley
PI Affiliation
University of Chicago

Additional Trial Information

Start date
End date
Secondary IDs
We construct a model of a worker's effort choice that includes altruism, warm glow and reciprocity towards employers, as well as the standard cost of effort and monetary incentive motives. We estimate the model using a natural field experiment with temporary workers. We design the experiment so as to structurally estimate the key parameters, using variation in pay schemes and the returns to the employers. Here, we register the analysis plan, including the fully specified structural model.

Update Sep 2018: We add to the registry as an attachment (in the Analysis Plan as well as in the Docs sections) a pre-registration of a follow-up experiment with a new, between-subjects design. This new experiment is entering the field towards the end of September 2018. We anticipate combining both the previously registered and completed experiment as well as the new pre-registered experiment in the same paper.
External Link(s)

Registration Citation

DellaVigna, Stefano et al. 2021. "Gift Exchange at Work." AEA RCT Registry. February 26.
Former Citation
DellaVigna, Stefano et al. 2021. "Gift Exchange at Work." AEA RCT Registry. February 26.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Effort exerted by workers in each session, measured as the number of envelopes stuffed (in each 20 minute session).
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We hire temporary workers for a single day's employment, and within the day vary pay and other features of the work within subject (across different sessions) and between subjects.
Experimental Design Details
We hire temporary workers for a single day's employment (about 5 hours of work) through posted ads on Workers prepare mailers -- i.e. fold and place materials in envelopes, working their way through a mailing list -- for fundraising and advertising campaigns. They work in ten sessions of 20 minutes each over the course of the day, for 4 different employers (three charities and one firm). The ten sessions include two training sessions where the prepared envelopes are not used, although the workers are paid for each envelope correctly prepared. Workers receive a single lunch break after the fourth work session of the day.
The different sessions vary the following aspects of the work:
1. The fixed amount ($0, $3.5 or $7) and piece rate per envelope ($0.20, $0.10 or $0 per envelope) paid to the workers
2. The return to the employer of the work ($0 in training session, $0.6 per envelope or $0.3 per envelope before wage costs), implemented in some sessions with a (truthfully implemented) "match" to the funds raised from the mailings.
3. The type of the employer (charity or firm)
4. An unanticipated "gift" in the final two sessions: Either a higher fixed pay ($14) than received previously (positive monetary gift), the same fixed pay ($7), a lower fixed pay ($3, negative monetary gift) or else an in-kind gift (a thermos with the logo of the employing charity) in addition to the basic fixed pay of $7 (in-kind positive gift). Assignment to positive, positive in-kind, negative and neutral gift treatments within each daily session happens by stratifying on worker performance in the first half of the day, as described below.
In each case, we observe the effort exerted by the worker. The response to variation in piece rates helps us identify the cost of effort function. The response of workers' effort to variation in the return to the employer helps identify and distinguish warm glow and pure altruism. The response to the gift treatments identifies the reciprocity parameters. Putting all the estimates together, we intend to determine the importance of worker altruism towards employers, and help interpret the magnitude of employees' positive or negative reciprocity to gifts.

The experiment uses two types of between-subject variation:
1. First, the order of the experimental sessions is randomized. There are 12 types of sessions, which vary (a) the session order (UP or DOWN), (b) the charity order (CHARITY ORDER 1, 2 or 3) in which one of the charities (B, RN or RIC) corresponds to Charity No 1 in the experimental design, and (c) the match order in the final two sessions (MATCH FIRST or MATCH LAST). This produces 2x3x2=12 treatment session types. The order of the 12 treatments was randomly drawn at the beginning of the study. We plan to hold at least 48 experimental sessions (of which 24 have already been completed as of the time of this posting) and ideally 72 total sessions if we can find enough subjects to recruit. In total, there will be at least 4 full loops through the complete set of 12 treatment sessions, and ideally 6 full loops. In any case, we will aim to run a completed loop though all the 12 sessions constituting one full run. On each day that the experiment is run, either one or sometimes two experimental sessions will be run (depending on how many individuals respond to the posted advertisement and show up).
2. The second randomization is at the individual level, within a given experimental session. Randomization occurs during lunch within an experiment session and is used to determine whether a subject is put into the positive gift, in-kind gift, negative gift, or control (neutral) gift treatment. The total number of envelopes each subject created in the previous sessions is totaled and their rank determined. The highest and lowest rank were put into one treatment, the second highest and second lowest were put into another treatment, and the middle two were put into the third treatment. In the very first experimental session, the highest and lowest rank were randomly placed in the negative gift. Following this, in the second group, the highest and lowest rank were place in the the neutral gift. In the third session, they were placed in the positive gift. This pattern was then repeated. Thus, the randomization was one-time and affected which treatment the first pair of "highest and lowest" workers were assigned to. After that, assignment was deterministic, although of course it depended on worker performance on a given day. The goal was the have ability be balanced over time in the different gift treatments combining over all the sessions, and as similar as possible on average even within a session.
NOTE: This experiment registration, including the full specification of the model and planned structural estimation, was written on 21 Nov 2014. This was after one full phase of data collection, with data on 131 subjects collected and two full rounds of treatment orders (that is, 24 sessions) completed. We plan to gather data on approximately 200 more subjects, making for a total of about 330 workers. But note that exact sample sizes will depend on (unpredictable) show-up of the invited workers. This will require collecting at least another two full rounds of treatment order sessions (T1-T12 twice over, in randomized order) and ideally four more full rounds (pending enough subjects to recruit). Notice that the only difference between the sessions run after Nov. 21, 2014 is the addition of an "in-kind gift" treatment, where workers are provided with an unanticipated gift (a thermos with the logo of the employing charity) in the gift periods, so the subjects are split four-ways in rounds 9-10. This treatment was not included in the first 24 sessions, since we thought of including this treatment after the initial 24 sessions.

In addition, we also utilize within-subject variation:
Each worker works for 10 work sessions in day, during which they face varying incentives. This provides a rich source of within subject variation.
The first of the ten work sessions for each subject is a training session, where the worker is paid to stuff practice envelopes, but the envelopes are discarded and not mailed by the employer (as always, there is no deception in the experiment, and the envelopes are truly discarded as announced to the workers). The fifth session, which is immediately after lunch, is a second training session. The last two sessions -- 9 and 10 -- are always the gift sessions, where workers receive unanticipated positive, negative, in-kind gifts or no gift. The remaining six sessions (other than the two training and two gift sessions) vary in order in one of two ways. Each subject is assigned to either UP or DOWN order, each of which specifies a particular sequence of the work sessions. Importantly, the two orders are reversed or mirror images of each other (excluding the position of the training and gift sessions, which are fixed). Particular pay scheme + employer combinations are thus observed (in different subjects) in two different positions -- once early and once late in the day. By averaging across these two occurrences, we can partially deal with issues of learning and tiredness over the course of the day.

Randomization Method
Randomization of treatment ordering by computer before start of experiment. More details in attachment, which becomes available after the end of the experiment
Randomization Unit
Individual level randomization and random ordering of treatments (i.e. randomization at the session level). Full details in the attachment, which becomes publicly available after the experiment is conducted.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Approximately 320 subjects, which might vary slightly due to unpredictable variation in no-shows by the invited potential workers. Of course, workers do not know their treatment status before showing up. While gift treatment varies at individual level, we can cluster standard errors at the experimental session level in the analysis.
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Approx 90 workers in each of treatment arm. Full details in attachment.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials


Document Name
Pre-registration of second follow-up experiment (Feb 2021)
Document Type
Document Description
After uploading this document, we will begin a second follow-up field experiment. This document explains the motivation and design of the new experiment.
Pre-registration of second follow-up experiment (Feb 2021)

MD5: 3d0b602f8c7d18163f9e872e76934cee

SHA1: c60b108f0a1995c052545651de9916cc596a9d69

Uploaded At: February 26, 2021

Document Name
Pre-registration of follow-up experiment (Sep 2018)
Document Type
Document Description
In Sep 2018, we will begin a follow-up field experiment. This document explains the motivation and design of the new experiment.
Pre-registration of follow-up experiment (Sep 2018)

MD5: 81fd688cf0cebd338368f9de84d86cca

SHA1: 77117b4c709043a2826c149fcb398f969fdf6d10

Uploaded At: September 21, 2018


Institutional Review Boards (IRBs)

IRB Name
Social and Behavioral Sciences Institutional Review Board at the University of Chicago
IRB Approval Date
IRB Approval Number
IRB Name
Social and Behavioral Sciences Institutional Review Board at the University of Chicago
IRB Approval Date
IRB Approval Number
Analysis Plan

Analysis Plan Documents

Analysis Plan - Exp Design, Model, Structural Estimation, Graphical Reduced Form Analysis

MD5: ca03ab4b5d51bba510804190875999f2

SHA1: c4abb6fb738c6e5bad1fd966063a6bc701c844c6

Uploaded At: November 23, 2014

Sep 2018 Update to Registration and Analysis Plan

MD5: 81fd688cf0cebd338368f9de84d86cca

SHA1: 77117b4c709043a2826c149fcb398f969fdf6d10

Uploaded At: September 21, 2018


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