Cohort studies differ from clinical trials in that no intervention, treatment, or exposure is administered to participants in a cohort design; and no control group is defined. Rather, cohort studies are largely about the life histories of segments of populations, and the individual people who constitute these segments.

Which of the following is NOT an advantage of a prospective cohort study? You cannot compute incidence rates or prevalence rates from case control studies.

Disadvantages of Prospective Cohort Studies You may have to follow large numbers of subjects for a long time. They can be very expensive and time consuming. They are not good for rare diseases. They are not good for diseases with a long latency.

 Ambispective cohort study- also known as a historical study, a cohort study that makes use of both retrospective features and prospective features.

Cohort studies are a type of medical research used to investigate the causes of disease and to establish links between risk factors and health outcomes. The word cohort means a group of people. These types of studies look at groups of people.

Ambispective study This is a very special kind of study where the observations are bidirectional (past and future both ) from the time point it begins. From the time point the study begins, it aims to look at future for what is going to happen next in the future course of illness.

A case-control study is designed to help determine if an exposure is associated with an outcome (i.e., disease or condition of interest). In theory, the case-control study can be described simply. First, identify the cases (a group known to have the outcome) and the controls (a group known to be free of the outcome).

An Ambidirectional Cohort Study The Air Force Health Study (AFHS) – also known as the Ranch Hand Study – was initiated by the U. S. Air Force in 1979 to assess the possible health effects of military personnel’s exposure to Agent Orange and other chemical defoliants sprayed during the Vietnam War.

Prospective and retrospective studies have different strengths and weaknesses. Prospective cohort studies are conducted from the present time to the future, and thus they have an advantage of being accurate regarding the information collected about exposures, end points, and confounders.

In the hierarchy used to classify evidence-based research in medicine, level 2 evidence includes prospective cohort studies. A prospective cohort study includes a research question developed prior to patient enrollment.

A cohort study can be prospective (researchers formulate their hypothesis before data collection). For a prospective cohort study, Level of Evidence = II. Or a cohort study can be retrospective (researchers formulate their hypothesis after data collection). For a retrospective cohort study, Level of Evidence = III.

In a health care context, randomised controlled trials are quantitative in nature, as are case-control and cohort studies. Surveys (questionnaires) are usually quantitative .

Descriptive research is usually defined as a type of quantitative research, though qualitative research can also be used for descriptive purposes.

Whereas the cohort study is concerned with frequency of disease in exposed and non-exposed individuals, the case-control study is concerned with the frequency and amount of exposure in subjects with a specific disease (cases) and people without the disease (controls).