Comparing healthcare utilization among health survey respondents with the total population - are respondents representative?

Compared to the total population, a greater proportion of survey respondents had made at least one outpatient visit to the doctor. However, the mean number of registered visits did not differ significantly between survey respondents and the total population. Hence, depending on the outcome measure used survey-based estimates may result in slightly biased prevalence estimates, however, relative differences among survey respondents were to a large degree comparable to relative differences in the total population. In contrast, survey respondents born outside Sweden differed from persons born outside Sweden in the total population to a degree where they may not be representative and comparisons between this group and other subgroups, using survey data, may be biased.