[Health survey in Campinas, São Paulo State, Brazil (ISACamp): comparison of estimates according to ownership of a residential telephone line].
ABSTRACT The study assesses differences in socio-demographic, lifestyle, and health-related characteristics among adults with and without residential telephone lines using data from a health survey in Campinas, São Paulo State, Brazil, (2008-2009), through a population-based cross-sectional survey that included 2,637 adults (18 years and older). Descriptive statistics, chi-square tests, prevalence, and 95% confidence intervals were used in the analysis. Estimates were also made of the bias associated with non-coverage of the population without telephones before and after adjusting for post-stratification. The impact of bias on the confidence intervals was assessed by the bias ratio. Some 76% of respondents owned residential telephone lines. Except for marital status, differences were observed in socio-demographic data according to ownership of residential telephones. After post-stratification adjustment, there was a decrease in bias estimates for variables associated with ownership of telephone lines. However, except for osteoporosis, post-stratification adjustment was insufficient to correct the non-coverage bias.