Exploring the feasibility of ex-post harmonisation of religiosity items from the European Social Survey and the European Values Study

This paper examines the feasibility of ex-post harmonisation strategies using European Values Study (EVS) Wave 5 (2017–2020) and European Social Survey (ESS) Round 9 (2018–2019) data across 17 countries. The study shows an empirical assessment of the comparability of four items measuring religious behaviours (belonging to a religious denomination at present/in the past, religious services attendance, and praying), captured in both surveys. The novelty of this paper lies in the analytical comparison of religiosity indicators that are rarely assessed from a comparative perspective. The harmonisation strategy was based upon several analytical techniques that seek to determine similarities and differences between the selected items in terms of (a) their validity, by examining their correlations with a set of sociodemographic and substantive correlates, (b) their distributions, supplemented by visual comparisons and relevant statistical tests, and (c) item non-substantive shares. The findings pointed to the most consistency among the partial correlations, where individual religiosity produced the most differences between the surveys. Distributions produced the most discrepancies that also corresponded to less similarity across variable categories as gauged by Duncan’s index. This paper is descriptive and exploratory in its aim. It can be taken as a jumping-off point for future research where the time series of these two surveys, and potentially others, can be examined across aggregate levels (e.g. birth cohorts, countries). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s42409-022-00038-x.