Analytic Epidemiology As noted earlier, descriptive epidemiology can identify patterns among cases and in populations by time, place and person. From these observations, epidemiologists develop hypotheses about the causes of these patterns and about the factors that increase risk of disease.
This is the expert reviewed version of this page, which is also the latest version. Analytical Study Designs Articles - Wiki Rate This Where descriptive epidemiology describes occurrence of disease or of its determinants within a population, the analytical epidemiology aims to gain knowledge on the quality and the amount of influence that determinants have on the occurrence of disease.
The usual way to gain this knowledge is by group comparisons. Such a comparison starts from one or more hypotheses about how the determinant may influence occurrence of disease. For example, the hypothesis may be "people who have eaten home preserved green olives in restaurant X in August have an increased risk of developing botulism than those who have not eaten such olives".
We can test this hypothesis in an analytical epidemiological study where the risk of developing botulism is studied in 2 comparable populations; one group consists of people that have visited restaurant X in August and who did eat green home preserved olives.
The other group consists of guests of restaurant X in August that have not eaten those olives. In both groups the risk of developing botulism is measured by counting botulism cases that occurred in each group within 30 days after visiting the restaurant.
Then those two risks are compared to see if they are significantly different. Observational studies In the above example of a simple analytical epidemiological study, a traditional cohort study design was chosen.
Another group of traditional study designs that belongs to analytical epidemiology are case control studies.
Other less traditional analytical study designs include case-case studies and case-cross over design. Choosing the appropriate reference group is one of the challenging aspects of analytical epidemiology. In such studies, the investigator observes systematically how exposure and outcome are distributed in the populations, and the comparison of those observations is made.
However RCT are not an option if the exposure is known to be very dangerous to humans, in which case it would not be ethical to conduct a RCT. In our example above, it is very clear that a RCT would be completely unacceptable i.
This often creates challenges in finding appropriate comparison groups.Epidemiologic case-control studies are used to identify factors that may contribute to a medical condition.
Epidemiological studies are categorized as either descriptive or analytic.
This course describes the main elements of descriptive and analytic epidemiology and their associated study types briefly and clearly. They differ from case-control studies in that they aim to provide data on the entire population under study, whereas case-control studies typically include only individuals with a specific characteristic, with a sample, often a tiny minority, of the rest of the population.
Case-control and cohort studies are observational studies that lie near the middle of the hierarchy of evidence. These types of studies, along with randomised controlled trials, constitute analytical studies, whereas case reports and case series define descriptive studies (1).
From an analytic viewpoint the cross-sectional study is weaker than either a cohort or a case-control study because a cross-sectional study usually cannot disentangle risk factors for occurrence of disease (incidence) from risk factors for survival with the disease. There are two common misconceptions about case-control studies: that matching in itself eliminates (controls) confounding by the matching factors, and that if matching has been performed, then a “matched analysis” is required.
However, matching in a case-control study does not control for. Case-control study – is one of the three basic analytical observational study designs. A case-control study starts by defining groups according to the outcome (e.g. disease present or absent) and then looks back to establish the study factor (e.g.
exposure present or absent).