The Welfare Effects of Woodwork Effects
Last registered on March 19, 2020


Trial Information
General Information
The Welfare Effects of Woodwork Effects
Initial registration date
March 17, 2020
Last updated
March 19, 2020 12:05 PM EDT
Primary Investigator
Other Primary Investigator(s)
PI Affiliation
Additional Trial Information
In development
Start date
End date
Secondary IDs
This experiment tests whether beliefs about means-testing of a social program affects individuals' attitudes towards the program.
External Link(s)
Registration Citation
Anders, Jenna and Charlie Rafkin. 2020. "The Welfare Effects of Woodwork Effects." AEA RCT Registry. March 19.
Experimental Details
The experiment will be embedded in a survey about the stigma around SNAP. Respondents will be given information intended to change their beliefs about the share of Americans who are eligible for SNAP.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Beliefs: We will ask survey respondents what they believe is the share of Americans overall who were eligible for SNAP in 2016.
Stigma index: We will ask respondents for the extent of their agreement or disagreement to eight statements which are intended to measure the stigma they perceive around food stamps.
Primary Outcomes (explanation)
The stigma instrument contains eight statements, and respondents indicate their agreement on a scale of 1 to 9. The scale does not increase with stigma for every statement; two will be reverse-coded.
To create the main outcome, we will aggregate responses to the eight statements. We will also create two subindices: one for self-stigma, which will include two of the eight statements, and one for social stigma, which will include four of the eight statements.
Secondary Outcomes
Secondary Outcomes (end points)
Attention check: We will ask survey respondents what the acronym “SNAP” stands for. This is a multiple choice survey question with four choices. We will use this to measure and adjust for inattention. We will also consider respondents inattentive if they report beliefs of overall eligibility outside the interval [1%,99%].
We will also evaluate effects on individual items in the stigma instrument.
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The experiment has a 2x2 randomization design. All respondents will be asked to report their beliefs about the share of Americans who had low enough income to qualify for SNAP in 2016. All respondents will be provided with a “hint,” which provides this statistic for “one U.S. state.” The first randomization (50/50) affects whether the hint corresponds to a state with a relatively high or relatively low eligibility share. The second randomization (50/50) involves a beliefs correction intervention, where we tell treatment respondents the true share of Americans who had low enough income to qualify for SNAP.

We will incentivize accurate belief reporting with the promise of a donation made to the charity of the respondent’s choice if their response is the closest to the truth (or, if they tie for the most accurate response, if they are chosen at random among those whose response is closest to the truth).
Experimental Design Details
Randomization Method
Computer/survey platform
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
No clustering
Sample size: planned number of observations
2,500 respondents
Sample size (or number of clusters) by treatment arms
625 in each of four treatment arms (2x2 randomization with equal probability)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Harvard University-Area Committee on the Use of Human Subjects
IRB Approval Date
IRB Approval Number
IRB Name
MIT Committee on the Use of Humans as Experimental Subjects
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers