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Cohort study. Prepared by Abdullah dwaikat . What is a cohort study?
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Cohort study Prepared by Abdullah dwaikat
What is a cohort study? • A Cohort Study is a study in which subjects who presently have a certain condition and/or receive a particular treatment are followed over time and compared with another group who are not affected by the condition under investigation.
A cohort is a group of people who share a common characteristic or experience within a defined period • The comparison group may be the general population from which the cohort is drawn, or it may be another cohort of persons thought to have had little or no exposure to the substance under investigation
One of the advantages of cohort analysis is that the study design does not require strict random assignment of subjects, which is, in many cases, unethical or improbable. • Cohort analysis is an appealing and useful technique because it is highly flexible. • it can be used with either original data or secondary data. In some instances, a cohort analysis can be less expensive than experiments or surveys.
The problem of cohort studies is that they can end up taking a very long time, since the researchers have to wait for the conditions of interest to develop. Researchers are, of course, anxious to have meaningful results as soon as possible, but another disadvantage with long studies is that things tend to change over the course of the study. People die, move away, or develop other conditions, new and promising treatments arise, and so on.
Because of the lack of randominization in the cohort design, the two groups may differ in ways other than in the variable under study. For example, if the subjects who smoke tend to have less money than the non-smokers, and thus have less access to health care, that would exaggerate the difference between the two groups.
Two examples of cohort studies that have been going on for more than 50 years are the Framingham Heart Study and the National Child Development Study (NCDS), the most widely-researched of the British birth cohort studies.