The multiple group IRT measurement invariance analysis of the Self-Compassion Scale in ten international samples

Abstract

The purpose of this study was to examine the measurement invariance of the Self-Compassion Scale by IRT differential test functioning in ten distinct populations (n = 13623 participants) from ten different countries: Australia (n = 517), China (n = 321), Czech Republic (n = 5081), Germany (n = 2510), Italy (n = 384), Portugal (n = 512), Slovakia (n = 1181), South Korea (n = 1813), Turkey (n = 471), and USA (n = 833). We assessed differential test functioning for the two SCS subscales, Self-compassionate responding and Self-uncompassionate responding separately, because previous bifactor and two-tier analyses of the scale showed the best fit with two separate general factors, and not for the overall score. Only 13 of the 45 comparisons for Self-compassionate responding and 13 of the 45 comparisons for Self-uncompassionate responding (analyses of every pair) demonstrated measurement invariance (no differential test functioning). Generally, our results revealed that the two subscales of Self-compassionate responding and Self-uncompassionate responding were not equivalent among all countries and groups. Therefore, it is impossible to compare overall scores across all countries. Two subscales of the Self-Compassion Scale (Self-compassionate responding and Self-uncompassionate responding) are valid and reliable instruments with substantial potential of use cross-culturally, but results reveal significant cross-cultural differences in the way these two constructs are measured by the subscales of the SCS. Future analyses of the meanings and connotations of this construct across the world are necessary to develop a scale which allows cross-cultural comparisons of various treatment outcomes related to self-compassion.