Gracia E, Martín-Fernández M, Lila M, Merlo J, Ivert A-K (2019) Prevalence of intimate partner violence against women in Sweden and Spain: A psychometric study of the ‘Nordic paradox’. PLoS ONE 14(5): e0217015. https://doi.org/10.1371/journal.pone.0217015
The high prevalence of intimate partner violence against women (IPVAW) in countries with high levels of gender equality has been defined as the “Nordic paradox”. In this study we compared physical and sexual IPVAW prevalence data in two countries exemplifying the Nordic paradox: Sweden (N = 1483) and Spain (N = 1447). Data was drawn from the European Union Agency for Fundamental Rights Survey on violence against women. To ascertain whether differences between these two countries reflect true differences in IPVAW prevalence, and to rule out the possibility of measurement bias, we conducted a set of analyses to ensure measurement equivalence, a precondition for appropriate and valid cross-cultural comparisons. Results showed that in both countries items were measuring two separate constructs, physical and sexual IPVAW, and that these factors had high internal consistency and adequate validity. Measurement equivalence analyses (i.e., differential item functioning, and multigroup confirmatory factor analysis) supported the comparability of data across countries. Latent means comparisons between the Spanish and the Swedish samples showed that scores on both the physical and sexual IPVAW factors were significantly higher in Sweden than in Spain. The effect sizes of these differences were large: 89.1% of the Swedish sample had higher values in the physical IPVAW factor than the Spanish average, and this percentage was 99.4% for the sexual IPVAW factor as compared to the Spanish average. In terms of probability of superiority, there was an 80.7% and 96.1% probability that a Swedish woman would score higher than a Spanish woman in the physical and the sexual IPVAW factors, respectively. Our results showed that the higher prevalence of physical and sexual IPVAW in Sweden than in Spain reflects actual differences and are not the result of measurement bias, supporting the idea of the Nordic paradox.
Intimate partner violence against women (IPVAW) remains a pervasive social and public health problem in western societies [1–8]. Increasing gender equality is at the core of the prevention efforts of this type of violence, as gender inequality is considered a main factor explaining IPVAW. Accordingly, rates of IPVAW are expected to drop as country-level gender equality increases [9–12] (see  for a review). However, in western countries, high country levels of gender equality are not always linked with low prevalence of IPVAW.
The high prevalence of IPVAW in countries with high levels of gender equality was defined by Gracia and Merlo as the “Nordic paradox” . Nordic countries are, according to different international indicators (e.g., Global Inequality Index; Global Gender Gap Index; European Index of Gender Equality), the most gender equal countries in the world [15–17]. However, despite these high levels of gender equality, Nordic countries have high prevalence rates of IPVAW. The high prevalence of IPVAW in Nordic countries is illustrated by a European Union (EU) survey on violence against women conducted by the European Union Agency for Fundamental Rights (FRA) . In this survey the average lifetime prevalence of physical and/or sexual violence by intimate partners in the 28 EU member states was 23%, with a range between 13% and 32%. However, Nordic countries in the EU were among the countries with higher lifetime prevalence of IPVAW, with rates of 32% (Denmark, the highest IPV prevalence in the EU), 30% (Finland), and 28% (Sweden). The high prevalence of IPVAW in Nordic countries is also supported by other studies and national surveys [19–25]. However, despite survey and research data pointing to a disproportionally high level of IPVAW in countries with the highest levels of gender equality like the Nordic ones, interestingly, this puzzling research question is rarely asked and, so far, remains unanswered.
The reasons explaining these high levels of IPVAW prevalence in Nordic countries, despite their high levels of gender equality, are not yet understood as almost no research has addressed specifically this paradox . Gracia and Merlo , proposed a number of theoretical and methodological lines of inquiry towards understanding the Nordic paradox. However, as these authors noted , a first step to ascertain whether the Nordic paradox reflects true differences in IPVAW prevalence is to rule out the possibility that measurement bias is causing prevalence differences between Nordic and other countries. To eliminate this possibility, a key question is to ensure the comparability of IPVAW prevalence data across countries. In other words, comparisons of IPVAW data across countries should not be made without first ensuring measurement invariance.
IPVAW can be a culturally sensitive issue, and the way this type of violence is perceived or reported may vary across countries. Therefore, ensuring cross-cultural measurement invariance is critically important for appropriate and valid cross-cultural comparisons of self-reported IPVAW scores between respondents from different countries [26–32]. As Jang et al. noted , different perceptions of items or different interpretations of response scales can lead to measurement non-invariance (i.e., non-equivalence of measures). If this is the case, it cannot be assumed that the construct of interest, in our case IPVAW, is interpreted in the same way across countries because the same score in one country may have a different meaning or reflect different levels of IPVAW in another. Without ensuring measurement invariance, score comparisons across samples from different countries can be unreliable and inadequate, and the validity of comparing women’s IPVAW experiences across countries becomes questionable [28,29,32,33].