ABSTRACT
Screening will be considered only for the purposes of research, and then only epidemiological research. In studies of the epidemiology of dementia, the prime purpose of screening is usually construed as improving the efficiency of case finding. Even assuming that criterion-based research diagnosis is unbiased with respect to demographic characteristics, the screening techniques may be biased and then transmit that bias to the diagnostic process. Statistical approaches to reducing the bias in screening instruments have been developed whereby items in scales can be selected for their relative neutrality with respect to demographic group membership. Identical screening techniques may be employed in geographically dispersed collaborative studies with the intention of comparing results from various locations and aggregating data across sites. Instruments that are used for screening at baseline may be expected also to provide data on the course of the illness by repetition at periodic intervals.
