Why carry out a cross-sectional study?
A cross-sectional study design is used when • The purpose of the study is descriptive, often in the form of a survey. Usually there is no hypothesis as such, but the aim is to describe a population or a subgroup within the population with respect to an outcome and a set of risk factors. • The purpose of the study is to find the prevalence of the outcome of interest, for the population or subgroups within the population at a given timepoint.Cross-sectional studies are sometimes carried out to investigate associations between risk factors and the outcome of interest. They are limited, however, by the fact that they are carried out at one time point and give no indication of the sequence of events — whether exposure occurred before, after or during the onset of the disease outcome. This being so, it is impossible to infer causality.The next four publications of Evidence-based Dentistry describe other study designs that may be more appropriate for the purposes of understanding associations
