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Field
Last Published
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Before
March 26, 2025 09:47 AM
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After
June 23, 2025 12:35 AM
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Field
Intervention (Public)
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Before
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.
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After
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 (i.e., their Prolific ID) to ensure confidentiality throughout the study.
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Field
Randomization Method
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Before
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.
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After
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 eight players (depending on session attendance) and are re-randomized into new pairs at the start of each bargaining period. In each period, they are matched to a new other participant with the opposite role. Participants may be matched with the same other participant in multiple rounds, but they will never be matched with the same participant in consecutive rounds and they are informed about it.
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Field
Randomization Unit
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Before
Matching groups of approximately six players (depending on session attendance)
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After
Participants will be matched into groups of 8 (4 informed, 4 uninformed) for the bargaining task. This group size balances statistical power, session feasibility, and real-time matching constraints.
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Field
Planned Number of Clusters
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Before
120 matching groups
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After
120 groups of 8 participants (N = 960), we expect to obtain 160 informed and 160 uninformed participants per phase.
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Planned Number of Observations
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Before
700 (350 informed players and 350 uninformed players)
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After
960 (480 informed players and 480 uninformed players)
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Field
Sample size (or number of clusters) by treatment arms
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Before
120
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After
120 groups of 8 participants (N = 960), we expect to obtain 160 informed and 160 uninformed participants per phase.
Menstrual Phase Assignment: Participants are pre-assigned to matching groups based on three menstrual phase categories—Ovulation, Pre-menstrual, and a combined Menstrual/Post-menstrual category—estimated using self-reported cycle data collected across prior survey waves. The matching logic prioritizes two objectives: (1) maximizing the inclusion of participants in the ovulation phase, given its short temporal window, and (2) maintaining approximate balance across phase categories and roles (informed/uninformed) within each 8-person group.
Assignment to sessions is based on the participants who are connected at the time of the session, and dynamic group formation is handled automatically by oTree. The platform allows for flexible, real-time allocation of participants into matching groups while preserving the intended balance in phase and role distributions whenever possible.
Although over 1,200 participants have been tracked, we conservatively plan for a final sample size of N = 960 to account for attrition and potential no-shows. This oversampling strategy increases the likelihood of forming complete, well-balanced groups during live sessions. All participants who attend a scheduled session will be matched following the same stratified randomization protocol, with priority given to maintaining the desired balance across menstrual phases and player roles.
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Field
Power calculation: Minimum Detectable Effect Size for Main Outcomes
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Before
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
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After
Participants will be matched into groups of 8 (4 informed, 4 uninformed) for the bargaining task. This group size balances statistical power, session feasibility, and real-time matching constraints. Based on power simulations, this structure allows us to reach our target distribution across menstrual phases with a manageable number of sessions. For example, with 120 groups of 8 participants (N = 960), we expect to obtain 160 informed and 160 uninformed participants. This yields 80 individual observations per treatment-phase cell, enabling us to detect a continuous effect size of d = 0.3 with 90.4% power and a 14 percentage point difference in deal rates with 84.4% power (α = 0.05), accounting for within-group dependence (i.e., assuming each observation reflects a group-level average for a given menstrual phase, rather than an individual-level measure).
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