Within a comprehensive comparison of telephone and postal survey methods the SF-8 was applied to assess adult's health-related quality of life. The 1690 subjects were randomly assigned to a telephone survey and a postal survey. Comparisons across the different modes of administration addressed the response rates, central tendency, deviation, ceiling and floor effects observed in the SF-8 scores as well as the inter-item correlation. The importance of age and gender as moderating factors was investigated. Results indicate no or small statistically significant differences in the responses to the SF-8 depending on the actual mode of administration and the health aspect questioned. It was concluded that further investigations should focus on the exact nature of these deviations and try to generate correction factors.
