 The Gothenburg H70 1930 birth cohort study found that the refusal rate increased with age. While participants compared with refusals had higher educational level, more often had osteoarthritis, had low mortality rates, had lower prevalence of neuropsychiatric alcohol related and cardiovascular disorders, and were more often married. Additionally, participants compared with same-aged individuals in Gothenburg had higher education and were more often born in Sweden, while those compared with same-aged individuals in Sweden had higher education, had higher average income, less often had ischemic heart disease, were less often born in Sweden and were more often divorced. This study showed that the participants were more representative of the target population in Gothenburg than they were of the same-aged individuals in Sweden, indicating that the study was more likely to be generalizable to the population it was studying.