Hannover Blood Donation Behavior Experiment

Last registered on October 30, 2023

Pre-Trial

Trial Information

General Information

Title
Hannover Blood Donation Behavior Experiment
RCT ID
AEARCTR-0012264
Initial registration date
October 15, 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
October 17, 2023, 1:50 PM EDT

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

Last updated
October 30, 2023, 4:51 AM EDT

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

Locations

Region

Primary Investigator

Affiliation
Harvard University

Other Primary Investigator(s)

PI Affiliation
Leibniz University Hannover
PI Affiliation
Leibniz University Hannover

Additional Trial Information

Status
In development
Start date
2023-10-16
End date
2024-12-25
Secondary IDs
H41; I1
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We analyze the supply curve (willingness-to-accept, WTA) using BDM alongside real opportunities for blood donation. We investigate how information about peer blood donation behavior affects supply and whether a respondent's own blood donation aligning (or not) with their identity group peers influences their identification with that group. We assess the persistence of such identity shifts, employing various identification measures, including two incentivized ones. Additionally, we explore how the perceived scarcity of one's blood impacts WTA as a secondary inquiry.
External Link(s)

Registration Citation

Citation
Chan, Alex, Annika Herr and Arndt Reichert. 2023. "Hannover Blood Donation Behavior Experiment." AEA RCT Registry. October 30. https://doi.org/10.1257/rct.12264-2.0
Sponsors & Partners

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information
Experimental Details

Interventions

Intervention(s)
We will assess willingness to donate blood and estimate the supply curve for blood using BDM linked to actual option for blood giving with the Red Cross afterwards. We then measure how the supply of blood can be shifted by peer behavior (information provision), and measure how concordance with actions with peers in a identity group shifts an individual's identity closeness using incentivized measures and a Likert scale score. We then measure the persistence of such identity closeness shifts, again with an incentivized measures tied to consequential decisions.
Intervention (Hidden)
Step 1: Elicit identity (Likert scale), trust by identity group (using the trust game where the counterpart would have different identities, e.g. female signaled via a female sounding name and feminine pronouns), and voting measure for identity affinity, at baseline in survey 1 --> THIS IS OUR BASELINE IDENTITY (captured by our Survey 1, attached as "LUH-Blooddonation - 1. Survey")
Step 2: In survey 2, provide prominent information about higher or lower peer giving rate (for wave 1, 4 arms: men, women, students of University of Hannover, no information/control) - e.g., "A survey conducted by the Leibniz University of Hannover in 2023 found that in the year before:
Men are over 4% more likely to donate blood than women." (see attached survey tool)
Step 3: For this edition of the experiment (done in person in the university), ask for blood type and provide either a “high scarcity awareness” or “low scarcity awareness” information treatment - information provision how rare their blood types are based on blood types.
Step 4: Use BDM to illicit willingness-to-accept without any priming (they can put any number) and ask about willingness to donate as a gift (ordering of these 2 questions in step 4 randomized) => map out supply curve and help quantify the effect of peer pressure treatment
Step 5: Elicit identity levels and trust again (identity (Likert scale), trust by identity group, and voting measure for identity affinity) --> THIS IS OUR POST-TREATMENT IDENTITY (steps 2-7 are captured by our Survey 2, attached as "LUH-Blooddonation - 2. Survey")
Step 6: Tell about actual payment (0 or 17 Euro) and give option to register for Nov. 6. - 17 was randomly drawn with the supervision of a Notary Public and based on what subjects submitted for the BDM, they will get paid 0 (if they put down a price higher than 17) or 17
=>linked to registration page that gathers Red Cross required information
Step 7: Actual donation decision, pay those who actually donated
Step 8: Elicit identity levels and trust again (identity (Likert scale), trust by identity group, and voting measure for identity affinity,) before Christmas --> THIS IS OUR LONG-TERM IDENTITY (captured by our Survey 3, attached as "LUH-Blooddonation - 3. Survey")
Intervention Start Date
2023-10-30
Intervention End Date
2023-12-23

Primary Outcomes

Primary Outcomes (end points)
There are 2 sets of primary outcomes:
(1) WTA for blood giving and willingness to donate blood as a gift with no payment
(2) Degree of identification to different identity groups (women/men, LUH student, and others) - 3 measures (differences in the identification score on a 1-7 Likert Scale, difference amount shared in a trust game, difference in number of points allocated to policy issues popular with female voters vs male votes)
Primary Outcomes (explanation)
The WTA for blood giving will just be based on BDM, and the price is denominated in Euros. Willingness to donate blood as a gift is a Yes/No question.

The Degree of identification to different identity groups (women/men, LUH student, and others) will be calculated in the following way:
measures (differences in the identification score on a 1-7 Likert Scale, difference amount shared in a trust game, difference in number of points allocated to policy issues popular with female voters vs male votes)

See attached files for more details, as well as attached pre-registered hypotheses below in "Experimental Design".

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Using an actual blood giving campaign, we elicit individuals' willingness-to-accept to give their blood (in Euros). We conduct a BDM to estimate the WTA. We also ask for willingness to donate blood as a gift (no payment). The main information provision experiment provides the participants with one of 4 treatments: control; information about the sub-sample of a survey where women are more likely to give blood than men; information about the sub-sample of a survey where men are more likely to give blood than women; and information about the sub-sample of a survey where LUH students are more likely to give blood than those who are not LUH students. The secondary provides some participants about how scarce their blood is or control. The decision to donate and the BDM is conducted after information provision. We measure how much participants identify with female/male/university identities using three different mechanism (including a Likert scale question, and two incentivized measures: trust game and voting task) - the key measure is the difference in the degree of identity affinity between the identity group of interest (e.g. women) and that of the other group (e.g. men).

An important pre-experiment study is one where we conduct a survey in Hannover, Germany to survey individuals about their blood giving behavior along with demographic information and other relevant information (e.g. music preferences to create a minimal group paradigm for latter versions of the experiment). (Attached as "LUH-Blooddonation-pre-survey")

Experimental Design Details
A few key hypotheses will be tested:
(1) H0: Blood Supply Curve is strictly monotonic and linear; H1: Blood Supply Curve is not strictly monotonic and non-linear (e.g. potentially "Nike"-checkmark-shaped characteristic of a "Pay enough or don't pay at all" mechanism)
- BDM results
- BDM results along with response to "gift-framed" question (e.g., if the respondent asked for a strictly positive price in BDM but agreed to give blood as a gift for free as well)
(2) H0: Information about high identity in-group giving does not lead to higher own blood giving (shift supply curve); H1: Information about high identity in-group giving leads to higher own blood giving (shift supply curve)
- Compare supply curves including testing if significant more giving for information treatment arm respondents at 0 and all price levels compared to control group (Cross-subject)
(3) H0: Identity affinity to a group for those who are not at extreme ends (very strongly identify or very strongly NOT identify with a group) stays the same before or after donation upon learning that it is identity-group-norm-concordant to donate; H1: Identity affinity to a group for those who are not at extreme ends increases after donation upon learning that it is identity-group-norm-concordant to donate
- we test by measuring relative identity affinity (to other identities) with the same mechanism weeks before the day of intervention/blood giving decision and testing if the difference is significant for those not in the top or bottom end in relative identity affinity (to other identities)
- One measure of identity affinity is a Likert scale question with each level accompanied by a graphic; the second measure is a trust game where the respondent will allocate money to another player whose only identifying characteristic is the name (gendered), the pronouns used for this other player, and whether this person attended the University of Hannover (this is incentivized, as random respondents would actual be paid based on their play and the response function elicited outside of the experimental session is real individuals with the name that match the ones used in the experiment); the third measure is an innovation where we ask individuals (who are Germans) to allocate 100 points across 6 US domestic, relatively obscure policy issues (e.g., should a standardized test be replaced in one state) to show their support for each issue - all these issues are real issues on the state ballots in 2024 - and based on which policy proposition received the most votes we will donate money to an organization that supports that issue (to incentivize the choice).
- we pre-register this hypothesis as testing the group not in the top decile/quartile or bottom decile/quartile to focus on those not at the extreme ends (a minor hypothesis here is that for those people who identify with their group in the top or bottom deciles/quartiles will not show an identity shift regardless of the information provision and blood giving decision)
(4) H0: Increase in identity affinity from (2) will not persistent in the longer term (4+ weeks after); H1: Increase in identity affinity from (2) will persistent in the longer term (4+ weeks after)
- we test two by measuring relative identity affinity (to other identities) with the same mechanism day of intervention/blood giving decision and 4+ weeks after (~6 weeks after) and testing if the difference is significant
(5) H0: Information about own blood being scare (not scarce) do not increase (decrease) own blood giving (shift supply curve); H1: Information about own blood being scare (not scarce) increase (decrease) own blood giving (shift supply curve)
- test for willing to accept less to give blood because non-financial motives

Actual surveys attached.
Randomization Method
Done by computer - LimeSurvey in-built function
Randomization Unit
individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
NA
Sample size: planned number of observations
About 850 participants for in person campaign (expecting 10-20% attrition for each round). Note that we plan to do a similarly sized and similarly designed experiment in early 2024 via an email campaign (this experiment might involve some modifications in the identity groups studied and minor design changes). This follow-up experiment will be separately pre-registered and that trial's pre-registration number will be added to this one upon its creation.
Sample size (or number of clusters) by treatment arms
Information about peer donation experiment
(1) ~212 control, ~212 information treatment about sample where women more likely donated than men, ~212 information treatment about sample where men more likely donated than women, ~212 information treatment about sample where University of Hannover students more likely donated than people who are not students of University of Hannover

Information about blood scarcity experiment (some attrition, as this is only for survey 2)
(2) ~359 in control, ~359 in treatment with information about blood scarcity
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information
IRB

Institutional Review Boards (IRBs)

IRB Name
Medizinische Hochschule Hannover Ethikkommission (Hannover Medical School Ethics Committee)
IRB Approval Date
2023-09-25
IRB Approval Number
11087_BO_K_2023

Post-Trial

Post Trial Information

Study Withdrawal

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials