Hi

you have to know how to write a research protocol steps. Cohort study design is 2 types: prospective and retrospective. Choose population and calculate sample size for 2 groups; exposed and non exposed.

For example: effect of smoking on both lungs.

So smokers in group A and non smokers in group B and check lung diseases` outcomes after 6 months at least or according previous studies period or as supervisors decided.

A cohort study is an observational research design where a group of individuals (cohort) is followed over a period of time to observe the occurrence of certain outcomes, such as disease development. In a cohort study, participants are classified based on their exposure to a specific factor, such as lifestyle habits, environmental conditions, or medical interventions. There are two types of cohort studies: prospective, where participants are followed from the present into the future, and retrospective, where past data is used to establish exposure and outcome relationships. To conduct a cohort study, researchers define the groups based on exposure status, dividing participants into "exposed" and "non-exposed" groups. The study then tracks the incidence of the outcome of interest (e.g., disease) in both groups over time. The effect of exposure is measured by comparing the outcome rates between these groups using statistical measures such as relative risk. Confounding variables, which may influence the relationship between exposure and outcome, are controlled through techniques like stratification or multivariate analysis. This approach helps establish the association between exposures and outcomes while maintaining a temporal relationship.