What is “Local”? A Lab-in-the-Field Experiment on Urban-Rural Differences in Willingness to Pay for Different Definitions of Local Food

Last registered on July 11, 2023

Pre-Trial

Trial Information

General Information

Title
What is “Local”? A Lab-in-the-Field Experiment on Urban-Rural Differences in Willingness to Pay for Different Definitions of Local Food
RCT ID
AEARCTR-0011587
Initial registration date
July 04, 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
July 10, 2023, 9:22 PM EDT

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

Last updated
July 11, 2023, 1:06 PM EDT

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

Locations

Primary Investigator

Affiliation
The Penn State University

Other Primary Investigator(s)

PI Affiliation
The Pennsylvania State University
PI Affiliation
The Pennsylvania State University
PI Affiliation
The Pennsylvania State University
PI Affiliation
The Pennsylvania State University

Additional Trial Information

Status
In development
Start date
2023-07-14
End date
2023-10-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
In this study, we aim to investigate the variations in willingness to pay for local and non-local potato chips among supermarket shoppers across different urban-rural landscapes, and the influence of different definitions of "local" on their purchasing decisions. We will conduct a lab-in-the-field experiment in Pennsylvania, focusing on supermarket shoppers in parking lots outside supermarkets situated in urban and rural areas. This approach will allow us to target supermarket shoppers and capture a diverse range of participants from various urban-rural landscapes.
External Link(s)

Registration Citation

Citation
Huang, Chiu-Lin et al. 2023. "What is “Local”? A Lab-in-the-Field Experiment on Urban-Rural Differences in Willingness to Pay for Different Definitions of Local Food." AEA RCT Registry. July 11. https://doi.org/10.1257/rct.11587-2.0
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Experimental Details

Interventions

Intervention(s)
In order to investigate (i) variations in the willingness to pay for local and non-local potato chips among supermarket shoppers across different urban and rural landscapes, and (ii) how different definitions of local affect their willingness to pay, we will set up a stand to recruit participants in supermarket parking lots in two different Pennsylvania locations, one urban and one rural. The study is open to those who meet the following criteria: are interested in buying potato chips and willing to join the experiment, are 18 years of age or older, and do not have a known allergy or intolerance to any ingredient typically found in potato chips. Qualified participants will be directed to a table near the recruitment site for the study.
Upon completing the study, participants will receive a $10 grocery gift card for compensation and $15 in cash for participating in a potato chip purchasing game at the end. Participants will complete a survey on tablets using the Qualtrics platform.
In the survey, participants will be randomly assigned to one of two treatment groups: one group will be informed that local potato chips are those produced within Pennsylvania, and the second group will be told that local potato chips are those primarily sold within Pennsylvania. We will explain the Becker-DeGroot-Marschak (BDM) method for willingness to pay on the survey screen, emphasizing that their indicated willingness to pay is not hypothetical and that the purchasing game is based on how much they indicate they are willing to pay. Participants will then be asked to indicate their willingness to pay for local and non-local potato chips based on the provided definition of "local". The price range for the chips is presented in increments of $0.10, from $0 to $15. Following this, participants will complete a brief survey about their attitudes towards local food, shopping habits, and demographic information. They will then go through the compensation process. Participants will be compensated with a $10 grocery gift card for attending and completing the experiment, plus $15 in cash for participating in a purchasing game. In this game, they may use part of the cash to purchase potato chips at a randomly selected price.
A drawing-like game will be used to determine whether a purchase is made. Two boxes, one for potato chip types and one for selling prices, will be presented. A potato chip type (local or non-local) will be randomly selected, followed by a selling price ranging from $0.5 to $15 in increments of 50 cents. If the participant's stated maximum willingness to pay for the chosen potato chips is equal to or greater than the randomly selected price, they can purchase the chips at the selected price using part of their $15 in cash. If their maximum WTP is lower than the selling price, no transaction will occur, and the participant will receive a $10 grocery gift card and $15 in cash, but no potato chips.
To prevent bias from brand preference, we will use two types of unbranded potato chips labeled as "local" and "non-local" in the game. The potato chips will be packaged in non-transparent bags to preclude brand identification .
Intervention Start Date
2023-07-14
Intervention End Date
2023-10-31

Primary Outcomes

Primary Outcomes (end points)
1. Willingness to pay for local potato chips
2. Willingness to pay for non-local potato chips
Primary Outcomes (explanation)
Willingness to pay for local and non-local potato chips: These variables measure how much participants are willing to spend on both local and non-local potato chips. They are continuous variables, ranging from $0 to $15. These outcomes will offer insights into how two alternative definitions of local influence consumer behavior and the perception of value. Furthermore, they will help determine whether geographical location and any associated lifestyle or environmental differences between participants significantly influence consumer preferences and the value assigned to local versus non-local food products.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
To test the influence of different definitions of "local," participants in this study will be randomly assigned to one of two treatment groups: (1) one group includes those told that local potato chips are produced in Pennsylvania, and (2) a second group includes those informed that local potato chips are primarily sold in Pennsylvania. Participants, who live in diverse landscapes, will be asked to indicate their willingness to pay for local and non-local potato chips based on the definition of local provided to them.

Once given these definitions, participants will indicate their willingness to pay for local and non-local potato chips based on the definitions, and then complete a short demographic survey.

Specifically, participants will denote how much they're willing to pay for a bag of local and non-local potato chips of the same flavor and approximately the same weight. Prices range from $0 to $15, in increments of $0.10. Given individual preferences, it is acceptable if participants choose not to pay anything for certain types of potato chips, which could indicate a strong dislike for that specific type. However, to avoid an excess of invalid responses (instances where the participant is unwilling to pay for any type of potato chips), we will inform potential participants at experiment locations about the opportunity to purchase potato chips and earn extra money.

Through a short survey, demographic information such as gender, race, age, food shopping habits, and attitudes toward local food will be collected. As we also aim to examine rural-urban differences, we will collect participants' addresses to ensure a diverse sample. No names will be collected, and all data will be analyzed anonymously and reported statistically.

Participants will use tablets to complete the survey on Qualtrics. The experiment will be conducted outside supermarkets in in two different locations, one urban and one rural, in Pennsylvania.

Participants will receive a $10 grocery gift card for attending and completing the experiment, along with $15 in cash for participating in a purchasing game. This game enables them to buy potato chips at a randomly selected price. The Becker-DeGroot-Marschak (BDM) method will be used to gauge participants' willingness to pay. Participants will be taught this method before they state their willingness to pay for chips in the survey. At the end of the experiment, participants may purchase one type of potato chip if the selling price is lower or equal to their stated maximum willingness to pay.

To determine whether a purchase occurs, a drawing-like game will be played. Two boxes will be provided with marked balls: one for potato chip types (local or non-local) and one for selling prices (ranging from $0.50 to $15 in increments of 50 cents). If the participant's stated maximum willingness to pay for the drawn potato chip type is greater than or equal to the drawn selling price, the participant will buy the potato chips at the selling price. Otherwise, no transaction will occur.

Two types of potato chips, without visible branding and labeled as "local potato chips" and "non-local potato chips", will be used to prevent brand preference from influencing decisions. Potato chips sold during the purchasing game will be provided in non-transparent bags to further prevent brand identification. All potato chips will be of the same flavor and approximately the same size and will be purchased from supermarkets.
The main goal of this study is to investigate whether the willingness to pay for local and non-local potato chips among supermarket shoppers varies based on different urban-rural landscapes, and whether different definitions of local affect these shoppers' willingness to pay for local potato chips. In addition to comparing the willingness to pay across the two treatment groups and examining variations between urban and rural landscapes, we also ask participants' personal definitions of local food through specific survey questions. This will allow us to explore whether these definitions vary across different landscapes. Through our research, we aim to deepen our understanding of consumer behavior and identify the factors that influence their willingness to pay for local products.
Experimental Design Details
Randomization Method
Randomization will be done by Qualtrics.
Randomization Unit
Individual will be the unit of randomization.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
400 respondents
Sample size: planned number of observations
200*2=400 respondents
Sample size (or number of clusters) by treatment arms
200 respondents per treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
Penn State Institutional Review Board
IRB Approval Date
2023-05-26
IRB Approval Number
STUDY00022765

Post-Trial

Post Trial Information

Study Withdrawal

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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