Public Perceptions of Inequality and Support for Redistribution: Evidence from a Survey Experiment in Croatia

Last registered on September 09, 2026
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Pre-Trial

Trial Information

General Information

Title
Public Perceptions of Inequality and Support for Redistribution: Evidence from a Survey Experiment in Croatia
RCT ID
AEARCTR-0019558
Initial registration date
September 01, 2026

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
September 09, 2026, 3:41 PM EDT

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

Locations

Country
Croatia
Region

Primary Investigator

Name
Marko Ledic
Affiliation
Ekonomski institut Zagreb
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Other Primary Investigator(s)

PI Name
Ivica Rubil
PI Affiliation
The Institute of Economics, Zagreb
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PI Name
Tibor Kovač
PI Affiliation
The Institute of Economics, Zagreb
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Additional Trial Information

Status
In development
Start date
2026-09-07
End date
2027-09-30
Keywords
Other
Additional Keywords
Inequality; redistribution; survey experiment; information treatment; policy preferences; Croatia
JEL code(s)
D31; D63; D72; D83; H24; H53; I38
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This project studies whether factual information about income inequality in Croatia affects public preferences for redistribution and preference for smaller income differences. We conduct a randomized online survey experiment with a planned final sample of 1000 valid completed respondents aged 18-65 in Croatia. Respondents are randomly assigned to receive factual information about the income distribution in Croatia or to a control condition. The main outcomes measure post-treatment inequality concern, support for government responsibility in reducing income differences, progressive income taxation, and social benefits for low-income people. The study estimates the average treatment effect of the information treatment, using assignment to treatment as the source of experimental variation, and examines heterogeneity by age, gender, income, education, and settlement size.
External Link(s)

Registration Citation

Citation
Kovač, Tibor, Marko Ledic and Ivica Rubil. 2026. "Public Perceptions of Inequality and Support for Redistribution: Evidence from a Survey Experiment in Croatia." AEA RCT Registry. September 09. https://doi.org/10.1257/rct.19558-1.0
Sponsors & Partners

Sponsors

Experimental Details

Interventions

Intervention(s)
Respondents assigned to the treatment group receive factual information about income inequality in Croatia based on official Eurostat/EU-SILC statistics. Respondents assigned to the control group receive a neutral message at the same point in the survey. The intervention is embedded in an online survey and is followed by outcome questions on inequality concern and redistributive preferences.
Intervention Start Date
2026-09-07
Intervention End Date
2026-09-30

Primary Outcomes

Primary Outcomes (end points)
The primary outcome consists of four redistributive-preference and inequality-concern outcomes measured on the original ordered response scales in the Croatian questionnaire: post-treatment inequality concern measured as the preferred direction of income differences in Croatia, support for government responsibility in reducing income differences, support for progressive income taxation, and support for increasing social benefits for people with low incomes. Binary versions of these outcomes will be used as robustness checks, not as the primary specification.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
None. Pre-treatment attitudes and beliefs, including q20, q21, and q22, will be used as covariates, balance variables, or heterogeneity variables.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The study is a randomized online survey experiment conducted through the Ipsos Croatian opt-in online access panel. Respondents first answer pre-treatment socio-demographic and attitudinal questions. They are then randomly assigned to treatment or control. After the treatment/control screen, all respondents answer post-treatment outcome questions on inequality concern and redistributive preferences.

The parameter of interest is the average treatment effect of exposure to the information treatment. If all respondents in the analysis sample receive the condition to which they are assigned, this equals the intention-to-treat effect of assignment to treatment. If there is any noncompliance or post-assignment exclusion, the assignment-based estimate will be interpreted as the intention-to-treat effect and exclusions will be documented.
Experimental Design Details
Not available
Randomization Method
Randomization will be implemented by Ipsos in the survey software during fieldwork. Assignment is at the individual level and targeted at a 1:1 treatment-control split. Randomization will be done within sample quotas defined by age group, gender, region, and settlement size, corresponding to blocked/stratified individual-level randomization within live quota management.
Randomization Unit
Individual respondent.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1000 individuals
Sample size: planned number of observations
1000 valid completed respondents after quality control. The target population is the Croatian resident population aged 18-65. The sample is a non-probability quota sample from the Ipsos Croatian opt-in online access panel, with quota targets set to reflect the corresponding distributions in the Croatian population aged 18-65. Panel members are compensated through Ipsos's standard panel incentive system.
Sample size (or number of clusters) by treatment arms

Approximately 500 respondents assigned to treatment and 500 assigned to control after quality control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
With approximately 500 respondents per group, the study is powered to detect moderate treatment effects in mean redistributive preferences and inequality concern. For a standardized individual outcome and equal treatment-control allocation, N = 1000 gives an approximate minimum detectable effect of about 0.18 standard deviations at alpha = 0.05 and power = 0.80. Binary outcome versions will be reported as robustness checks where useful.
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
Ethics Committee of The Institute of Economics, Zagreb
IRB Approval Date
2026-06-10
IRB Approval Number
Ref. no. 114-04/26-01/01, Reg. no. 251-467-2-26-18
Analysis Plan

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