Measurement invariance of the Arizona Sexual Experience Scale by sexual orientation: comparing the sexual functioning of gay and heterosexual individuals

Background: The assessment of sexual functioning requires accurate and reliable measures as well as short and easy to apply. The Arizona Sexual Experience Scale (ASEX), which provides a quick, easy, and nonintrusive assessment of sexual functioning in men and women, is a clear example of a commonly used scale that satisfies these qualities. Aim: The study sought to examine measurement invariance and differential item functioning (DIF) by sexual orientation of the Spanish version of the ASEX. Methods: A confirmatory factor analysis was performed on a sample of 1600 adults (800 gay and 800 heterosexual individuals), testing measurement invariance of the ASEX by sexual orientation in men and women separately, and calculating its reliability and DIF. Outcomes: The measure provided by the Spanish version of the ASEX is reliable and valid for assessing the sexual functioning of gay men and lesbians, but comparisons by sexual orientation are not recommended for men. Results: The results of the confirmatory factor analysis confirmed the unidimensional structure of the ASEX already found in the Spanish validation with heterosexual people. Measurement invariance showed that, in the men's sample, the factor structure of the ASEX only reached the weak level of invariance, whereas in the women's sample, strict invariance by sexual orientation was reached. The internal consistency reliability was adequate, with better coefficients in women than in men. No significant DIF was observed in either men or women. Clinical Implications: Clinicians should further their training in sexual and gender diversity as approaches such as affirmative LGBT psychotherapy gain popularity, and they must have access to assessment instruments that are psychometrically robust enough to be used with this population. Strengths and Limitations: This research has some limitations. Because the distribution was administered solely through social media platforms, those without access to social media were unable to participate. Beyond these restrictions, however, the findings are thought to be significant from a research and clinical perspective since measurement invariance is a step that is often excluded when using an instrument validated in a mostly heterosexual sample. Conclusion: Validating assessment tools in gay men and lesbians is essential because sexual functioning is a crucial concept in sexual health. The findings of this study suggest that the Spanish version of the ASEX offers valid and reliable measures of sexual functioning for both heterosexual and gay people, though there would be bias in comparing men of both orientations.