14.3.2  Types of observational studies

As a Health Extension Practitioner you will probably only be directly concerned with observational studies. These generally take the form of sample surveys (of selected individuals) or population surveys (covering everyone in the population), where the sample or the population is observed for various characteristics. This may be done by interviewing study subjects, using questionnaires or focus groups, by obtaining measurements of physical characteristics (e.g. height or age), or by simply extracting information from existing sources, such as disease registries or hospital records. The most common type of study design you will be involved in is the observational survey, in which information is systematically collected from your study population on a specific topic.

There are three types of observational survey which are most likely to use if you conduct a small-scale research project, and each has a different study design. They are:

• cross-sectional study
• case-control study
• cohort study.

These are just three of many types of research study. These three will be covered in more detail in the sections that follow.