Figure I. Graphical representation of permutation tests. The first test permutates the data for each HPV type individually and derives the expected distribution of HPV positivity assuming full independence for all HPV types. The second test permutates the data for the set of HPV types within each genus and derives the expected distribution of HPV positivity assuming independence between genera while maintaining the clustering of types within a genus. Table I. Betapapillomavirus time-averaged prevalences and incidence rates, overall and by type, age, and lifetime number of sex partners.