AEA RCT Registry

Trial Information

General Information

Title

The Impact of the Menstrual Cycle on Bargaining Behavior

RCT ID

AEARCTR-0015476

Initial registration date

March 24, 2025

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

March 26, 2025, 9:47 AM EDT

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

Locations

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Primary Investigator

Name

Lina Lozano

Affiliation

NYU Abu Dhabi

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Other Primary Investigator(s)

PI Name

Arno Riedl

PI Affiliation

Maastricht University

Contact Investigator

PI Name

Christina Rott

PI Affiliation

Vrije Universiteit Amsterdam

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Additional Trial Information

Status

In development

Start date

2025-03-24

End date

2025-07-25

Keywords

Behavior, Gender, Labor

Additional Keywords

bargaining, asymmetric information, menstrual cycle, biological factor

JEL code(s)

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

We investigate experimentally how the menstrual cycle affects bargaining behavior and bargaining outcomes of women. Female participants negotiate in an unstructured bilateral bargaining game with asymmetric information about the allocation of a surplus ('pie size'). Our study provides first evidence that biological factors affect bargaining. The study is approved by the Ethical Review Committee of Psychology and Neuroscience (ERCIC\_651\_24\_01\_2025) at Maastricht University.

External Link(s)

Registration Citation

Citation

Lozano, Lina, Arno Riedl and Christina Rott. 2025. "The Impact of the Menstrual Cycle on Bargaining Behavior." AEA RCT Registry. March 26. https://doi.org/10.1257/rct.15476-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

The study consists of two phases. The first phase involves tracking participants’ menstrual cycles over a three-month period. Participants are recruited three months before the online bargaining session, during which they report the start date of their last menstruation. Using this information, along with their average cycle length over the tracking period, we estimate the start of their next menstrual cycle. A three-month tracking period is necessary, as medical literature suggests this is the minimum duration required for accurate cycle measurements.

In the second phase, participants take part in an online bargaining experiment. They are randomly assigned to anonymous pairs and engage in a bargaining game over ten rounds. Each participant is given a unique anonymous ID to ensure confidentiality throughout the study.

Intervention Start Date

2025-03-24

Intervention End Date

2025-07-25

Primary Outcomes

Primary Outcomes (end points)

Measures of the bargaining process and outcomes:

For the bargaining process, we analyze informed players' initial offers, uninformed players' initial demands, and both players' concessions during bargaining. Initial offers and demands capture an individual's bargaining attitudes before they are affected by the negotiation partner's behavior. To investigate the interactive nature of bargaining, we look at concessions during the simultaneous bargaining stage.

Bargaining outcomes are measures of negotiation success. We analyze negotiators' final payoffs, deal rates, and payoffs conditional on reaching an agreement.

Primary Outcomes (explanation)

Initial offers and demands are the proposals made by informed and uninformed players in the initial bargaining phase, which are made in private and before they start interacting with the other player.

Concessions are changes in offers and demands, respectively, that show a negotiator's willingness to give up part of their own stake to reach an agreement and make the bargaining partner better off.

Conditional payoffs are the payoffs conditional on reaching an agreement. Deal rates refer to the frequency of agreements, and Final payoffs are the payoffs including disagreement.

Secondary Outcomes

Secondary Outcomes (end points)

We collect data on (i) demographics (e.g., age, education, and work status) and (ii) risk and social preferences. These variables will be used as controls to assess the robustness of our analysis.

As a robustness check, we will also adjust the window frame for ovulation. This approach will help assess the sensitivity of our findings and further reinforce the robustness of our study's conclusions. Furthermore, to ensure the reliability and validity of our findings, we will incorporate a self-reported measure of bargaining to complement the results obtained from the behavioral measure.

Finally, as an additional robustness check, we will perform the entire analysis separately for informed and uninformed players, using bootstrapped cluster-robust standard errors with 1,000 repetitions.

Secondary Outcomes (explanation)

Experimental Design

The study consists of two phases. The first phase involves tracking participants’ menstrual cycles over a three-month period. Participants are recruited three months before the online bargaining session, during which they report the start date of their last menstruation. Using this information, along with their average cycle length over the tracking period, we estimate the start of their next menstrual cycle. A three-month tracking period is necessary, as medical literature suggests this is the minimum duration required for accurate cycle measurements.

In the second phase, participants take part in an online bargaining experiment. They are randomly assigned to anonymous pairs and engage in a bargaining game over ten rounds. Each participant is given a unique anonymous ID to ensure confidentiality throughout the study.

Experimental Design Details

Not available

Randomization Method

Participants are randomly assigned to the roles of informed and uninformed players in the bargaining game and maintain the same role throughout the 10 bargaining periods. In addition, they are grouped into matching groups of approximately six players (depending on session attendance) and are re-randomized into new pairs at the start of each bargaining period.

Randomization Unit

Matching groups of approximately six players (depending on session attendance)

Was the treatment clustered?

No

Experiment Characteristics

Sample size: planned number of clusters

120 matching groups

Sample size: planned number of observations

700 (350 informed players and 350 uninformed players)

Sample size (or number of clusters) by treatment arms

120

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Our objective is to recruit approximately 360 informed and 360 uninformed players, evenly distributed across three menstrual phases: Ovulation, Pre-menstruation, and a combined category for Menstrual and Post-menstrual phases. We aim to detect an effect size of approximately 0.2, with a targeted statistical power of 95% at a significance level of 0.05 to rigorously test our primary hypotheses related to the bargaining process and outcomes

Supporting Documents and Materials

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