Final answer:
The Historical Prospective Cohort Study uses historical data to establish a baseline exposure level and follows subjects into the future. This method combines aspects of a prospective study with those of a retrospective study and requires careful planning to be effective.
Step-by-step explanation:
The study design that uses historical data to determine exposure level at a specific baseline in the past is known as a Historical Prospective Cohort Study. In this type of study, a group of subjects (the cohort) is identified based on their exposure status as of a past date and then followed into the future to determine the occurrence of outcomes. Unlike a retrospective cohort study or case-control study which look back in time to gather data, the historical prospective cohort study combines elements of both by starting with historical data and then tracking outcomes going forward.
Observational studies like the cohort study can be prospective, meaning researchers follow the subjects into the future, or retrospective, meaning they look at past data to draw conclusions. The choice of study design is crucial, as it impacts the accuracy of the data and the cost and complexity of conducting the research. Prospective cohort studies are generally more costly and require more resources than their retrospective counterparts, but they are also more likely to yield accurate data since they track progression of disease or conditions over time.
To understand the different types of observational studies such as cross-sectional, case-control, and cohort studies, and to determine which is most appropriate for a given research question, is essential in planning original research designs. Proper planning of the research design provides a framework to analyze both anticipated and unanticipated data effectively.