Boxplot of age differences between partners by participant’s gender and age group. Denominator: opposite-sex partners in the past year reported by Natsal-3 participants aged 16–74 y who reported 1+ opposite-sex partners in the past year, data on ≥1 opposite-sex MRPs in the MRP module, and the age of their MRP(s). Unweighted N=13 604 partners (5 867 men’s partners; 7 737 women’s partners); Weighted N=16 201 partners (8 816 men’s partners; 7385 women’s partners).