Study design

This chapter aims to present an overview of the various types of epidemiological study designs available to the researcher.D esign options in epidemiology may be classified according to different criteria, for instance the condition of observation (experimental versus observational), the unit of data collection and analysis (group versus individual), or the time dimension (cross-sectionavl ersusl ongitudinal). As can be seen (table 1) the classification in the present chapter is performed according to the unit of data collection. Intervention studies may be based on both group and individual data and are hence presented separately. The advantages and limitation of different study design are important, are often debatabie and are emphasized in the text. Examples of the varies study design are given. Finally the chapter contains a practical approach fo'tlie inexperienced researcher for how to plan and conduct an epidemiological survey. The present chapter does not intend to cover these areas in full detail. For such a purpose the reader is encouraged to consult available textbooks and scientific journal publications.