Is Longer Always Better? A Comparison of the Validity of Single-item Versus Multiple-item Measures of Life Satisfaction

The aim of this research was to examine the validity of a single-item life satisfaction scale by comparing it with the Satisfaction with Life Scale (SWLS). Three studies were conducted on a total of six samples of Serbian undergraduate students, adults, and elderly (total N = 2822). We examined: 1) correlations between a single-item measure of life satisfaction and the SWLS; 2) convergent and criterion-related validity of the two measures; 3) age and gender differences in life satisfaction as measured with the two measures; 4) test-retest reliability of the two measures. The SWLS and the single-item measure were strongly correlated across six samples (mean r = .70). The validity of the two scales was supported, and they generally yielded similar correlations with other constructs. The 10-month test-retest reliability (intraclass correlation coefficient) was .56 for the SWLS, and .43 for the single-item scale. No consistent gender differences were observed in life satisfaction as measured by both scales among students and adults, but men reported substantially higher life satisfaction than women on SWLS among the elderly. We found that age differences in life satisfaction can depend on the scale used. The present findings support the use of single-item scales of life satisfaction, but also highlight a need for more research beyond validity and reliability of single-item life satisfaction measures.