Cross-Sectional Study/ Prevalence Study
Definition: A cross-sectional study is a descriptive study in which disease and exposure statuses are measured simultaneously in a given population. This study type can be thought of as providing a "snapshot" of the frequency and characteristics of a disease in a population at a particular point in time. Data that are collected as part of a cross-sectional study can be used to assess the prevalence of acute or chronic conditions in a population.
Advantages to Cross-Sectional Studies
- Does not require follow-up and is therefore less costly and quicker than other designs.
- Are often representative of a population, rather than a smaller sub-population.
Disadvantage of Cross-Sectional Studies
- Since exposure and disease status are measured at the same time it is not possible to determine the direction of the association. In other words, it is not known if the exposure preceded the disease and is therefore a potential cause of disease.
Example: A cross-sectional study can be used to look at the association between obesity and television watching. A sample of people from the population that you are interested in can be polled and asked about their height/weight ratio and the number of hours of television the person watches each week. This study will give insight as to whether obesity and television watching are associated, but it will not help to determine which might cause the other. In other words, it is not known if obesity causes more television watching or if more television watching causes obesity.
