Correlation between prevalence of infection and response rate. There was a significant positive correlation between the 2 variables (simple Pearson coefficient r = 0.3510, P = .018). The equation of the line relating response rate (y) and prevalence of infection (x) is estimated as: y = (7.2148) + (0.6744) x. The slope (r correlation coefficient), that is, the estimated change in response rate per unit change in the prevalence of infection, is 0.6744 with a standard error of 0.3058. The value of R², the proportion of the variation in the response rate that can be accounted for by variation in the prevalence of infection, is 0.2038. The lower limit of the 95% CI for the slope is 0.0343 and the upper limit is 1.3144. The estimated intercept is 7.2148. The lower limit of the 95% CI for the intercept is −36.2226 and the upper limit is 50.6521 (curved dotted lines).