Simultaneous Estimation of the Incidence and Prevalence in a Two-Phase Longitudinal Sampling Design by

Two-phase sampling design is a common practice in many medical studies with rare disorders. Generally the first-phase classification is fallible but relatively cheap, while the accurate second-phase state of-the-art medical diagnosis is complex and rather expensive to perform. When constructed efficiently it offers great potential for higher true case detection as well as for higher precision. In this paper we consider epidemiological studies with two-phase sampling design. However instead of a single two-phase study we consider a scenario where a series of two-phase studies are done in a longitudinal fashion. Efficient and simultaneous estimation of prevalence as well incidence are being considered at multiple time points from a sampling design-based approach. Finally efficacy of the developed method is discussed with special reference to a study of dementia among the elderly population.