Supplement Figure 4 Kaplan-Meier failure curve for age at marriage for men and women. Data include all reports after corrections and estimations for inconsistent reports. had never been married (50.3% vs 26.8%, x2 test, p,0.001). Participants who reported having ever been married or in a long- term relationship were asked at what age they first entered such a relationship. Of these, 43 (0.72%), 45 (0.85%) and 59 (0.55%) did not respond to the question regarding age at marriage in the first, second and third surveys, respectively. Of the individuals who reported an age at marriage, 68% (9874/14 508) only reported it in one round. Reports were classed as unreliable for 33.2% of women and 52.5% of men who reported age at marriage in at least two surveys (fig 1). Of these unreliable reports, 26.5%, 17.8% and 13.7% of reports differed by 2, 3 and 4 years, respectively. The remaining 41.9% of reports differed by .4 years. Excluding unreliable reports when plotting failure curves did not change the overall trends when compared with trends based on all reports (regardless of consistency). The median age at marriage remained largely unchanged when unreliable reports were excluded (table 2). Figure 3 Median estimates of reported age at first sex by 5-year birth cohort for (A) men and (B) women. IQR, interquartile range. Data include all reports after corrections and estimations for inconsistent reports. The upper value of the IQR could not be calculated for those born after 1975 as 60% of men and 60% of women born after 1975 reported not having had sex. Table 3 Median age at first sex and number reporting (N) for men and women reporting in at least two surveys by 5-year birth cohort and age group Birth cohort Before 1955 1955–9 1960–4 1965–9 1970–4 After 1975 Men 15–19 17.0 (415) 18.8 (68) 18.0 (1047) 19.3 (45) 19.0 (609) 18.3 (458) 19.0 (48) 19.0 (352) 19.0 (388) 19.5 (23) 19.0 (379) 19.3 (231) 20.0 (22) 20.0 (257) 19.0 (239) 45–49 20.0 (224) 20.0 (172) Women 15–19 17.0 (448) 18.0 (62) 18.0 (1103) 20–24 25–29 30–34 35–39 40–44 20–24 25–29 30–34 35–39 40–44 Data include all reports after corrections and estimations for inconsistent reports have been made. Small sample sizes are indicated in italic, along the leftmost diagonal for men and for women. These are low due to the timing of the surveys in relation to birth cohorts (eg, the majority of individuals in the 1970–4 birth cohort had aged past the 20–24 age group when they were surveyed). Sex Transm Infect 2009;85(Suppl I):i34–i40. doi:10.1136/sti.2008.033431 18.0 (69) 18.3 (750) 18.6 (586) 18.3 (65) 18.3 (656) 18.3 (599) 19.0 (50) 18.0 (816) 18.0 (496) 19.3 (42) 19.0 (667) 18.0 (671) 45–49 19.0 (436) 18.7 (544) i37