Observational (cross-sectional and longitudinal) studies

This chapter concentrates on observational studies with a specific focus on two different types of observational study: cross-sectional studies and longitudinal studies in relation to the area of physical activity research. There are fundamental differences between cross-sectional studies and longitudinal studies from an observational study perspective and this chapter seeks to make these differences clear for the reader. In terms of how these two types of study are used in physical activity, examples of physical activity research are provided within the chapter to aid understanding. Key considerations in the design and use of these two types of observational study are also included in the chapter. The chapter concludes with the authors providing a case study of physical activity research which utilized both a cross-sectional and longitudinal observational study design.