Table 2. Sensitivity analysis, by HPV type and country.

		Sensitivity Index ¶
		HPV16		HPV18
Parameter		Italy	Sweden	Italy	Sweden
Probability of transmission		0.481	0.588	0.641	0.581
Rate of clearance (r(t))*	a	0.23	0.002	0.003	0.003
	b	0.07	0.068	0.07	0.07
	c	0.15	0.186	0.19	0.19
	r(t) *	0.45	0.256	0.263	0.263
Assortativeness	Age	0	0.136	0.136	0.136
	Sexual activity	0.003	0.007	0.007	0.007
Probability of developing life-long immunity after HPV infection clearance	Boys	0.032	0.007	0.007	0.007
	Girls	0.033	0.005	0.007	0.007
Adjusted R-squared		0.21	0.16	0.16	0.16

Relative importance (sensitivity index) of input parameters of the transmission model.

^*where r _(t)= a*EXP(-b*t)^c and t is time elapsed since infection.

^¶The sensitivity index of each input parameter corresponds to the proportion of the total variance attributable to each parameter in multivariable quadratic regression model, where each set of input parameters of the transmission model was treated as a vector of independent variables and the log-likelihood, measuring the fit between model’s estimate and observed data, acted as dependent variable. The sensitivity index of each parameter takes values between 0 and 1. The higher is the sensitivity index the more influent is the parameter on the fit between transmission model estimates and observed data.

Abbreviation: HPV = human papillomavirus