A cross-section plan is an observational study design. In a cross-sectional study, the investigator simultaneously measures the outcome and the exposures of the study participants. In contrast to the case-control studies (participants chosen based on outcome status) or cohort studies (participants selected based on exposure status), participants in a cross-sectional study are determined solely based on the inclusion and exclusion criteria. The cross-sectional plan is used in population-based surveys to assess disease prevalence in clinic-based samples. These studies are typically conducted in a relatively short period and at a low cost. They can be used to plan a cohort study or as a baseline in a cohort study.