Fig. 4

Results of cumulative-link mixed model with condom use as the outcome. In this model age difference was a spline term. a. cumulative probability of condom use categories for age difference. b. predicted effect of age difference on ordinal condom use score (scored as 0 for “never” up to 2 for “every time”), with shaded areas representing the 95% CI. c. proportional odds ratio (POR) and 95% CI plot for non-spline terms in the model