Cross-Sectional Study: The Role of Observation in Epidemiological Studies

Commonly arising from empirical observations or from opportunistic case reports/case series, a cross-sectional study is often the first step in a planned investigation of exposure–disease associations. Being relatively quick and inexpensive, a cross-sectional study is a widely used epidemiological study design in public health research. This study design overcomes many of the limitations of other descriptive study designs, such as ecological studies, and can provide an evidence base for further analytical epidemiological studies. Cross-sectional studies, therefore, play an important role in the examination of health data and hypothesis formulation. Additionally, they may be used to provide initial evidence of causality. This chapter will explain the conceptualization, conduct, and interpretation of cross-sectional studies. This chapter will detail: (1) the purpose and roles of cross-sectional study designs in public health, (2) the common methods of data collection used for exposures and outcomes, (3) calculations of measures of disease association in cross-sectional studies, (4) strengths and limitations of this study design, and (5) common uses of cross-sectional studies in public health and policy. This chapter will compare cross-sectional studies with other types of study designs to highlight the types of real-world research questions that can be answered. We will also describe the conditions under which cross-sectional studies can be used to test the causal associations between exposures and outcomes.