 Naaman's bias, also known as prevalence incidence bias, is a type of bias in research. Naaman's bias occurs when there is a higher enrollment of prevalent cases with longer disease duration over the incident new cases. For example, in a study on a chronic disease conducted over a short period, participants with a longer disease duration are more likely to be included, leading to a higher observed prevalence. Naaman's bias can be minimized by selecting cases and controls from the same time frame using a longitudinal study design and analyzing and reporting the study results separately for prevalent and incident cases.