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Determinants of Public Support for Supply Management: A Randomized Survey Experiment

Last registered on December 06, 2018
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Pre-Trial

Trial Information

General Information

Title
Determinants of Public Support for Supply Management: A Randomized Survey Experiment
RCT ID
AEARCTR-0003632
Initial registration date
December 04, 2018

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
December 06, 2018, 8:27 AM EST

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

Locations

Country
Canada
Region

Primary Investigator

Name
Ryan Cardwell
Affiliation
University of Manitoba
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Chad Lawley
PI Affiliation
University of Manitoba
Contact Investigator

Additional Trial Information

Status
In development
Start date
2018-12-10
End date
2019-12-31
Keywords
Agriculture
Additional Keywords
supply management, information treatment, randomized controlled trial
JEL code(s)
C90 D04 D31 Q18
Secondary IDs
Abstract
We conduct a survey, with an experimental component, among voting-eligible Canadians to investigate determinants of support for a Canadian food policy called supply management. The experimental component involves randomly assigning respondents to either a control group, or to receive one of three treatments, each of which receives different information on the costs and distributional effects of supply management on consumers. The information treatment on consumer costs is customized to individual recipients’ household characteristics to increase salience. We also randomize the estimated food price increases that result from supply management policies. Detailed information is collected from participants, including household demographics, political preferences, perceptions of other Canadians’ incomes, support for other food policies, and preferences for government redistribution. We investigate correlation between respondent characteristics and support for supply management, and use the experimental structure of our survey to identify causal effects of information treatments on support for supply management. We will estimate interaction effects between treatments and respondent information, including support for redistribution, political affiliation, and views on related food policies.

The survey also includes a section that asks respondents’ preferred level of compensation for farmers, if supply management were to be dismantled. Respondents will be presented with estimated annual costs of compensation (a tax bill) and estimated annual benefits (lower prices).

We also plan a follow-up survey several months after collecting data from the first-round questionnaire. The follow-up will allow us to observe the persistence of treatments from the first round. The follow-up will also include a question that gauges whether a change in respondents’ preferred political party’s position on supply management affects voting behaviour.
External Link(s)

Registration Citation

Citation
Cardwell, Ryan and Chad Lawley. 2018. "Determinants of Public Support for Supply Management: A Randomized Survey Experiment." AEA RCT Registry. December 06. https://doi.org/10.1257/rct.3632-1.1
Former Citation
Cardwell, Ryan and Chad Lawley. 2018. "Determinants of Public Support for Supply Management: A Randomized Survey Experiment." AEA RCT Registry. December 06. https://www.socialscienceregistry.org/trials/3632/history/199713
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Participants are recruited by the polling firm Ekos to be representative of the Canadian population along the dimensions of province and income. The survey will be conducted in English and French. A screening question will allow only those who are eligible to vote in Canada to participate.
Intervention Start Date
2018-12-10
Intervention End Date
2019-04-30

Primary Outcomes

Primary Outcomes (end points)
Level of support for supply management, effect of information on support for supply management.
Primary Outcomes (explanation)
Support for supply management is captured through a referendum question on whether to maintain or dismantle supply management. Effect of information on support for supply management is identified by randomising treatments across participants.

Secondary Outcomes

Secondary Outcomes (end points)
Level of support for different compensation options for farmers if supply management were dismantled. Assess the extent to which changes in stated support for supply management by an individuals preferred political party will affect that individual’s support for the political party.
Secondary Outcomes (explanation)
Participants will be presented with a table of options of compensation levels for farmers if supply management were to be dismantled. One preferred choice will be selected. Table will include estimated costs and benefits for participants. Cost and benefit information in this table are customised based on respondents’ estimated expenditures on supply managed products, and on estimated price effects after dismantling.

A follow up survey will be conducted. This survey will be similar to the first round survey is most respects. A new question in the follow up survey will ask participants to suppose that their preferred political party (based on their answer to a previous question) has changed their position on supply management. Respondents will then be asked to indicate which party they would be most likely to vote for in a federal election.

Experimental Design

Experimental Design
Our survey instrument collects detailed information on respondents, including household characteristics, opinions on food policies, views on income redistribution, and political preference.
Respondents are randomly assigned to one of four groups in the first round of the survey:
1. Control group – no information treatment
2. Treatment group 1 – customised information on household costs due to supply management
3. Treatment group 2 – information on distributional effects of supply management on consumers
4. Treatment group 3 – combined information from previous two treatments.
Experimental Design Details
Randomization Method
Respondents are randomly assigned to one of four groups using the Voxco software platform.
Randomization Unit
Not clustered.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1
Sample size: planned number of observations
5,000 respondents
Sample size (or number of clusters) by treatment arms
1,250 respondents in the control group and each of the three treatment groups.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
University of Manitoba Joint-Faculty Research Ethics Board
IRB Approval Date
2018-11-28
IRB Approval Number
Protocol #J2018:060 (HS20555)
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
July 18, 2019, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
July 18, 2019, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
5409
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
5409
Final Sample Size (or Number of Clusters) by Treatment Arms
1332 control, 1342 treatment 1, 1361 treatment 2, 1384 treatment 3
Data Publication

Data Publication

Is public data available?
No

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Program Files

Program Files
No
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials