An epidemiological study usually involves two important steps that must be put into consideration prior to the investigation of disease/infection outbreak. The first step in any epidemiological study is to define the hypothesis to be tested. The hypothesis must take into consideration the description of the exposure and possible outcome of the disease. The second step is to determine the type of epidemiological study design to adopt, and which will be most appropriate to test the already defined hypothesis.
In the course of anticipating any epidemiological survey, the type of epidemiological study design adopted by an epidemiologist (or public health workers, researchers or those involved in disease surveillance) is a fundamental decision that must be made and chosen carefully.
This is because there are varieties of available study designs for epidemiological investigations, and each of this study designs differ in their merits and demerits. Epidemiological investigations can be directed towards revealing the determinants of a disease or describing the way and manner in which the disease/infection is being distributed within a defined population/community.
The different types of available and applied epidemiological studies reflect the diver’s ways or means of gathering information or data in the scenario of a disease/infection outbreak. The preference of one type of study design over another is usually centered on the ethical issues surrounding the anticipated study, the validity of the study, its efficiency and research questions to be addressed.
It should be noted that disease/infection does not just happen in a space or vacuum but rather a host (i.e. an individual) and other environmental factors are paramount to the establishment of a disease state in a given population/community. Because of this, epidemiologists therefore rely on systematic or logical approach in the investigation of disease distribution within a community.
Thus, epidemiological study designs allows for the determination of disease agents in a classified manner while putting in place appropriate preventative measures to forestall disease emergence and spread to unexposed members of the population/community.
As an epidemiologist or researcher anticipating an epidemiological study, it is very critical to take into consideration the most appropriate epidemiological study design to be adopted, and this must encompass factors such as the cost of the study, its practical feasibility, duration of the study and the expected data or result.
Based on these facts, epidemiological studies can be broadly divided into two categories which are:
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