Epidemiological research methods. Part II. Descriptive studies
The original publication is available at http://www.samj.org.za
In a descriptive study, therefore, the magnitude and distribution of a health problem in a specified population is studied in terms of TIME (when did it occur?), PLACE (where did it occur?) and PERSON (which groups are affected?). The design starts with an idea that occurs to the researcher about a particular problem. This is followed by selecting a group of individuals to be studied (sampling), considering which attributes to measure (measurement), describing the findings, and finally drawing conclusions on the basis of the findings. Commonly, new ideas or hypotheses are generated in this final stage, usually regarding possible explanations for the health problems described (cause-effect relationships). Such relationships may be attempts to explain the aetiology of diseases or the effect of preventive, curative or rehabilitative measures. Important issues affecting the reliability of the sampling and measurement processes are discussed, some descriptive statistical measures demonstrated and how conclusions are affected by these, are indicated.
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