Factor structure and measurement invariance of the Women's Health Initiative Insomnia Rating Scale.

TLDR

The Women's Health Initiative Insomnia Rating Scale (WHIIRS) was developed as part of the Women's Health Initiative Study. The scale was derived from a 10‑item sleep questionnaire completed by postmenopausal women, using a novel resampling technique and principal‑axes factor analysis on 120,000 random samples of 1,000 women each. Analysis of 66,269 women produced a highly stable 5‑item factor structure with no major differences across age or race‑ethnicity, and WHIIRS norms for these subgroups are provided.

Abstract

As part of the Women's Health Initiative Study, the 5-item Women's Health Initiative Insomnia Rating Scale (WHIIRS) was developed. This article summarizes the development of the scale through the use of responses from 66,269 postmenopausal women (mean age = 62.07 years, SD = 7.41 years). All women completed a 10-item questionnaire concerning sleep. A novel resampling technique was introduced as part of the data analysis. Principal-axes factor analysis without iteration and rotation to a varimax solution was conducted for 120,000 random samples of 1,000 women each. Use of this strategy led to the development of a scale with a highly stable factor structure. Structural equation modeling revealed no major differences in factor structure across age and race-ethnic groups. WHIIRS norms for race-ethnicity and age subgroups are detailed.