Anchoring and time pressure in preference elicitation

Last registered on June 24, 2023
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Pre-Trial

Trial Information

General Information

Title
Anchoring and time pressure in preference elicitation
RCT ID
AEARCTR-0011468
Initial registration date
June 11, 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
June 23, 2023, 3:43 PM EDT

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

Last updated
June 24, 2023, 8:09 AM EDT

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

Locations

Country
Greece
Region
Athens

Primary Investigator

Name
Andreas Drichoutis
Affiliation
Agricultural University of Athens
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Achilleas Vassilopoulos
PI Affiliation
Agricultural University of Athens
Contact Investigator

Additional Trial Information

Status
In development
Start date
2023-06-12
End date
2023-10-31
Keywords
Behavior
Additional Keywords
second price auction, willingness-to-pay
JEL code(s)
C91, D12
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Consumer preferences for fig jams will be elicited in order to estimate WTP values associated with attributes of Short Food Supply Chains (SFSC), namely related to number of intermediaries and distance from the production area. Subjects are recruited from the population of Athens, Greece and participate in a second price auction where they bid to buy 400 gr of a jar of fig jam. Subjects are randomly assigned to one of the following treatments, where we vary on a between-subjects basis the jams available for auction. Subjects bid simultaneously for two of the jams:

Treatment 1: Jam purchased directly from the producer and production area is at a Shorter distance vs. Jam purchased from an intermediary and production area is at a Shorter distance
Treatment 2: Jam purchased directly from the producer and production area is at a Shorter distance vs. Jam purchased directly from the producer and production area is at a Longer distance
Treatment 3: Jam purchased from an intermediary and production area is at a Longer distance vs. Jam purchased from an intermediary and production area is at a Shorter distance
Treatment 4: Jam purchased from an intermediary and production area is at a Longer distance vs. Jam purchased directly from the producer
and production area is at a Longer distance

Subjects go through three rounds of auctions. In the first round they have no information about the attributes of the jams and they are asked to bid based on appearance only. In Round 2, they receive information about the jams and in Round 3 they get to taste the jams before they bid.

Moreover, to test the effect of anchoring and how it might prevail with time pressure, subjects receive a randomly determined initial bid. They are then given either a short amount of time to adjust their bid or a longer amount of time to adjust it with the understanding that if time expires, the standing bid is the binding bid. Subjects will be randomly assigned to a time limit of 20, 30, 40 or 50 seconds, which will remain constant across all rounds.
External Link(s)

Registration Citation

Citation
Drichoutis, Andreas and Achilleas Vassilopoulos. 2023. "Anchoring and time pressure in preference elicitation." AEA RCT Registry. June 24. https://doi.org/10.1257/rct.11468-1.1
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Subjects receive a 30 Euro coupon for participation and then participate in a zero counting task for 10 rounds, where they can earn up to 50 cents per round, so that they make up to 5 Euros by round 10. They are told from the beginning that for only 1 subject in each group their decisions will be realized and only for that subject earnings from the zero counting task and winnings from the auction are realized.

Subjects are randomly assigned to one of the following treatments, where we vary on a between-subjects basis the fig jam available for auction. Subjects bid simultaneously for two of the jams:

Treatment 1: Jam purchased from the producer - Closer distance vs. Jam purchased from the retailer - Closer distance
Treatment 2: Jam purchased from the producer - Closer distance vs. Jam purchased from the producer - Further distance
Treatment 3: Jam purchased from the retailer - Further distance vs. Jam purchased from the retailer - Closer distance
Treatment 4: Jam purchased from the retailer - Further distance vs. Jam purchased from the producer - Further distance

Subjects go through three rounds of auctions. In the first round they have no information about the attributes of the jams and they are asked to bid based on appearance only. In Round 2, they receive information about the jams and in Round 3 they get to taste the jams before they bid. The overall design combines elements of within- and between-subjects design.

In each auction round subjects receive a random determined default bid drawn between {0, 3.5} euros. Subjects will be randomly assigned to a time pressure of 20, 30, 40 or 50 seconds with the understanding that the standing bids will be the binding ones after time expires.
Intervention Start Date
2023-06-12
Intervention End Date
2023-10-31

Primary Outcomes

Primary Outcomes (end points)
Bids and bid deviations from the the initial randomly drawn bid.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Subjects receive a 30 Euro coupon for participation and then participate in a zero counting task for 10 rounds, where they can earn up to 50 cents per round, so that they make up to 5 Euros by round 10. They are told from the beginning that for only 1 subject in each group their decisions will be realized and only for that subject earnings from the zero counting task and winnings from the auction are realized.

Subjects are randomly assigned to one of the following treatments, where we vary on a between-subjects basis the fig jam available for auction. Subjects bid simultaneously for two of the jams:

Treatment 1: Jam purchased from the producer - Closer distance vs. Jam purchased from the retailer - Closer distance
Treatment 2: Jam purchased from the producer - Closer distance vs. Jam purchased from the producer - Further distance
Treatment 3: Jam purchased from the retailer - Further distance vs. Jam purchased from the retailer - Closer distance
Treatment 4: Jam purchased from the retailer - Further distance vs. Jam purchased from the producer - Further distance

Subjects go through three rounds of auctions. In the first round they have no information about the attributes of the jams and they are asked to bid based on appearance only. In Round 2, they receive information about the jams and in Round 3 they get to taste the jams before they bid. The overall design combines elements of within- and between-subjects design.

In each auction round subjects receive a random determined default bid drawn between {0, 3.5} euros. Subjects will be randomly assigned to a time pressure of 20, 30, 40 or 50 seconds with the understanding that the standing bids will be the binding ones after time expires.
Experimental Design Details
Randomization Method
Randomizations are performed by the computer. The between-subjects treatments are randomized for the first 4 sessions but then are assigned on an alternating basis in order to even out morning and evening sessions for all treatments.
Randomization Unit
Group of subjects at the session level for the between-subjects treatments. Initial bid and time pressure are randomly assigned to subjects on an individual basis.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
0
Sample size: planned number of observations
75 subjects * 4 treatments * 3 rounds * 2 bids at each round = 1800 observations
Sample size (or number of clusters) by treatment arms
75 subjects per each of the between-subjects treatments (4 treatments)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
With N=75 subjects/treatment we can detect a difference of at least d=0.3 in bids for a sigma = 0.7 and an Intra-class Correlation Coefficient across rounds of up to 0.7. Values for sigma and bids can only be assumed as we could not locate studies on WTP for jam in the literature. For smaller values of sigma (e.g., sigma=0.5) and rho (e.g., rho=0.5), N=75 subjects/treatment can detect smaller differences e.g., d=0.2.
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Agricultural University of Athens
IRB Approval Date
2023-05-23
IRB Approval Number
37/16.05.2023
Analysis Plan

Post-Trial

Post Trial Information

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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