Final answer:
Cohort studies are expensive and complex because they involve long-term tracking of a group, requiring significant resources for data collection and management. They also face challenges in ensuring diverse group representation, which can be difficult and add to the cost and logistical demands.
Step-by-step explanation:
A significant disadvantage of cohort studies in terms of price and groups involved is their cost and complexity. Cohort studies require tracking a group of similar subjects—known as a cohort—over an extended period, which can be months or even years. This commitment of time and resources makes them more expensive and challenging to manage than other types of observational studies like cross-sectional research. The substantial financial burden stems from the need to regularly collect data, follow up with participants, and manage the extensive database of information that accrues over time. Moreover, ensuring the representation of various groups within the cohort can be difficult, particularly if the groups involved have differing levels of accessibility or engagement.
It's important to note that in a cohort study, participants typically share key characteristics at the start of the research; so, contrary to what might be suggested in the True or False statement, they are not necessarily comprised of subjects with different ages, weights, genders, and health statuses, but rather are selected to be as similar as possible in relevant aspects. This helps in addressing specific research questions but can also limit the generalizability of the findings to broader populations due to potential homogeneity within the cohort.