Evaluation of the factorial and metric equivalence of the Sexual Assertiveness Scale (SAS) by sex

Sexual assertiveness refers to the ability to initiate sexual activity, refuse unwanted sexual activity, and use contraceptive methods to avoid sexually transmitted diseases, developing healthy sexual behaviors. The Sexual Assertiveness Scale (SAS) assesses these three dimensions. The purpose of this study is to evaluate, using structural equation modeling and differential item functioning, the equivalence of the scale between men and women. Standard scores are also provided. A total of 4,034 participants from 21 Spanish provinces took part in the study. Quota sampling method was used. Results indicate a strict equivalent dimensionality of the Sexual Assertiveness Scale across sexes. One item was flagged by differential item functioning, although it does not affect the scale. Therefore, there is no significant bias in the scale when comparing across sexes. Standard scores show similar Initiation assertiveness scores for men and women, and higher scores on Refusal and Sexually Transmitted Disease Prevention for women. This scale can be used on men and women with sufficient psychometric guarantees.