Characterizing Unstructured Bargaining - A Lab Experiment

Last registered on May 13, 2024

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Pre-Trial

Trial Information

General Information

Title

Characterizing Unstructured Bargaining - A Lab Experiment

RCT ID

AEARCTR-0013593

Initial registration date

May 13, 2024

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

May 13, 2024, 12:47 PM EDT

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

Locations

Country

Switzerland

Region

Zurich

Primary Investigator

Name

Mia Lu

Affiliation

University of Zurich

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Martin Stancsics

PI Affiliation

University of Zurich

Contact Investigator

Additional Trial Information

Status

In development

Start date

2024-05-14

End date

2024-05-16

Keywords

Behavior, Lab

Additional Keywords

Bargaining

JEL code(s)

Secondary IDs

Prior work

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

Abstract

How can we characterize the outcomes of unstructured bargaining? We study unstructured bargaining in a lab experiment where one party has significantly more bargaining power. Players bargain in groups of three via chat. We test how well standard concepts from cooperative game theory can characterize outcomes, focusing on the Shapley value and the nucleolus.

External Link(s)

Registration Citation

Citation

Lu, Mia and Martin Stancsics. 2024. "Characterizing Unstructured Bargaining - A Lab Experiment." AEA RCT Registry. May 13. https://doi.org/10.1257/rct.13593-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

Intervention Start Date

2024-05-14

Intervention End Date

2024-05-16

Primary Outcomes

Primary Outcomes (end points)

Player A's payoff (see below for the definition of player A)

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

Other player's payoffs
Proposal history
Chat logs
Survey answers

Secondary Outcomes (explanation)

Experimental Design

- Bargaining: Every round, subjects play a coalitional game in groups of three. Subjects are assigned different player roles, one role (Player role A) has significantly more bargaining power than the other two; player A is needed to create any value. Subjects bargain over which coalition to form and how the created value is allocated between coalition members. Bargaining is free-from and takes place over chat.
- Real effort task: Subjects play a slider task before the bargaining rounds in order to motivate the assignment of bargaining power. Better performance on the task leads to a higher probability of becoming player A.
- Matching groups: We reshuffle bargaining groups within matching groups every round. The reshuffling is predetermined in order to minimize overlap between bargaining groups across rounds.

Experimental Design Details

- Treatments: We vary the characteristic function of the coalitional game. We have four treatments in total. In the first three treatments we vary the value that a two-player coalition between Player A and one of the other two players can create. The fourth treatment is a dummy player treatment: one of the players is a dummy player, adding this player does not add any value to the coalition (the other two players on their own already create the same value as the grand coalition).
- Role assignment: Within a bargaining group roles are assigned as follows: Players are ranked according to their performance in the task. The best-performing player becomes player A with probability 0.5, the second-best performing player with probability 0.3 and the worst-performing player with probability 0.2 (in the dummy player treatment this is reversed, with the worst-performing player becoming the dummy player with probabilitiy 0.5, the second-best performing player with probability 0.3 and the best-performing player with probability 0.2). Ties are broken randomly.

For the full instructions and implementation see https://github.com/stanmart/unstructured-bargaining-experiment/releases/tag/main-experiment (git commit hash: 64ae48773a3fcfff1d7af74e1c9b60d4082ddcd7).

Randomization Method

Randomization done by a computer

Randomization Unit

Experimental sessions

Was the treatment clustered?

Yes

Experiment Characteristics

Sample size: planned number of clusters

24 matching groups

Sample size: planned number of observations

240 (24 matching groups, each matching group has two three-player-groups every round, and there are 5 rounds) for the primary analysis. 720 (each of the 240 group-round observations include one observation for each group member) for secondary questions.

Sample size (or number of clusters) by treatment arms

6 matching groups (clusters) by treatment arm

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

Supporting Documents and Materials

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