An information experiment about the Swedish EITC
Last registered on September 10, 2020


Trial Information
General Information
An information experiment about the Swedish EITC
Initial registration date
September 09, 2020
Last updated
September 10, 2020 4:17 AM EDT

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Primary Investigator
Uppsala University
Other Primary Investigator(s)
Additional Trial Information
On going
Start date
End date
Secondary IDs
Economic models of labour supply usually assume perfect, or at least constant, knowledge about tax policy, even though most economists would agree that we should expect stronger responses when policy is well-known. This neglect is understandable, given that no one knows how important such knowledge is. To fill this gap, we have conducted an experiment in which we sent half of all new parents in Sweden information about the Swedish EITC, in Swedish called Jobbskatteavdraget. Using Swedish registry data we will analyze how this treatment affected labor supply as well as the division of parental leave between the spouses.
External Link(s)
Registration Citation
Nyman, Pär. 2020. "An information experiment about the Swedish EITC." AEA RCT Registry. September 10.
Experimental Details
In March 2018 we delivered a letter which was sent to half of all Swedish mothers who had given birth between 1 June 2017 and 31 January 2018. The letter included information about the Swedish EITC and how the size of this tax credit increases with the size of an individual’s earned income. The purpose of this intervention is to analyze how information about the tax system affects economic behavior.

The information in this letter is described in more detail in the attached analysis plan.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
In our main analysis, we will look at the following four outcomes (exact definitions are provided in the analysis plan):
- The mothers' earned income.
- Employment among both mothers and fathers.
- The couples' joint earned income,
- The distribution of parental leave between the mother and the father.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The sampling frame consisted of all mothers to children born between 1 June 2017 and 31 January 2018. These 74,667 individuals were randomly allocated to a treatment group (n = 37, 334) and a control group (n = 37, 333).
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer. The randomization was conducted by Statistics Sweden.
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
74,667 couples (identified by the biological mother), equally distributed between treatment and control.
Sample size (or number of clusters) by treatment arms
37,334 in treatment and 37,333 in control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Regionala Etikprövningsnämnden Uppsala
IRB Approval Date
IRB Approval Number
Dnr 2017/026/1
IRB Name
Regionala Etikprövningsnämnden Uppsala
IRB Approval Date
IRB Approval Number
Dnr 2017/026
Analysis Plan
Analysis Plan Documents
Pre-analysis plan

MD5: c158648b9dd576887819be285e587fb9

SHA1: f286afa7663508553c84b28b23972ae40e7073a6

Uploaded At: September 09, 2020