We examine variance estimators of a binomial parameter established under cluster sampling using data from a cross-sectional study of bovine trypanosomosis in Mukono County, Uganda. Fifty farms (referred to as clusters), were sampled with a total sample size of 487 cattle. Trypanosomes were found in 17.9% (87/487) of the total sample. The cluster-level (CL) prevalences were not homogeneously dis...

The leprosy control programme in Indonesia is discussed . The epidemiological situation of leprosy is assessed from the statistics of the registered cases and through comparison of several leprosy surveys. In a certain province leprosy showed a marked decline, while in other provinces the prevalences are still high. We need to recognize the limitations of the present measures employed to contro...

PURPOSE Causal effects in epidemiology are almost invariably studied by considering disease incidence even when prevalence data are used to estimate the causal effect. For example, if certain conditions are met, a prevalence odds ratio can provide a valid estimate of an incidence rate ratio. Our purpose and main result are conditions that assure causal effects on prevalence can be estimated in ...

Socially important visual search tasks, such as airport baggage screening and tumor detection, place observers in situations where the targets are rare and the consequences of failed detection are substantial. Recent laboratory studies have demonstrated that low target prevalence yields substantially higher miss errors than do high-prevalence conditions, in which the same targets appear frequen...

SETTING Right of entry may sometimes be denied to immigrants because of the threat of tuberculosis. During 1990-2000 some 1050000 immigrants, mostly from countries highly endemic for TB, arrived in Israel, a low prevalence country. Nevertheless, TB rates in Israel have remained low. OBJECTIVE To emphasise the challenge beyond technical competence for TB control for immigrants from the perspec...