Reach me, if you can: How to Boost Participation of Rich Households in Wealth Surveys?

Andrej Cupak
National Bank of Slovakia & University of Economics in Bratislava

Judita Jurašeková Kucserová
National Bank of Slovakia

Zuzana Brokešová
University of Economics in Bratislava

Boris Frankovič
Statistical Office of the Slovak Republic

Sofie R. Waltl
University of Cambridge

Abstract

Extensive evidence shows that differential non-response in wealth surveys leads to the under-representation of rich households, biasing aggregates and distributional measures. This article proposes and experimentally tests a targeted, incentivized oversampling strategy in the 2023/24 wave of the Slovak Household Finance and Consumption Survey (HFCS). The design distinguishes between a general population sample and a rich population sample; households in the rich sample are randomly assigned to incentivized and non-incentivized groups, with a valuable collector’s silver coin offered as a participation incentive. The incentive increases participation among wealthy households by 11–16 percentage points and raises the effective oversampling rate of the top 10% from −18 in 2021 to 48.2 in the current wave. The intervention shifts the measured wealth distribution upward, increasing the Gini index by 2.3% with oversampling alone and by 6.5% when incentives are added suggesting that survey-based comparative inequality measures may be strongly distorted due to different sampling choices adopted across Europe. Employing both oversampling and incentives substantially reduces the gap between survey totals and National Accounts aggregates. Response quality does not differ significantly between treatment and control groups, while personal interviewer interaction improves data quality relative to purely online modes.

JEL Codes: C83, C93, D31.
Keywords: HFCS, survey experiment, missing wealthy households, unit-non-response, over-sampling, incentives.

Dissemination

Presentations (incl. scheduled): [Slovak Economic Association Meeting (SEAM), Bratislava, SK][2nd LIS/III Comparative Economic Inequality Conference, Luxembourg][NBS – National Bank of Slovakia][University of Economics, Bratislava][HFCN meeting, Bank of Greece, Athens][Conference “Inequalities and Opportunities — Insights into wealth, income and education disparities”, University of Bari][International Conference on Wealth Inequality: The Munich International Stone Center for Inequality Research (ISI), LMU Munich][CNB – Czech National Bank][NOeG Winter Workshop, Vienna][Economic Statistics Centre of Excellence (ESCOE) at King’s Business School][39th IARIW General Conference, National Bank of Belgium]

Panel Discussion: Social Situation Monitor (SSM), Brussels