Age dependence of parameter estimates.

<p><b>a.</b> Estimated detectability by age (Model A and triplet model), and Williams mean parasite densities by age group assessed by microscopy. The grey area is the 95% confidence envelope for the detectability. (The Williams mean of <i>N</i> observed densities <i>y</i> is calculated as ). <b>b.</b> Observed mean multiplicity of infection (MOI) by age group in northern Ghana and estimated MOI allowing for imperfect detection. MOI was determined from PCR positive blood samples only. <b>c.</b> Estimated average duration of an infection by age group (Model A). Error bars are approximate 95% confidence intervals. <b>d.</b> Estimated force of infection by age group (Model B). Estimates are rates expressed relative to that in the oldest age group. Error bars are approximate 95% confidence intervals.