Final answer:
A clinical trial is a type of research study involving interventions to evaluate health outcomes, unlike cohort studies, which are observational without researcher intervention.
Step-by-step explanation:
A clinical trial is any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes. Clinical trials are characterized by the use of experimental conditions to test the efficacy of medical interventions such as drugs, devices, or procedures. Cohort studies, in comparison, are a type of observational study where a group of subjects, known as the cohort, is followed over time to observe health outcomes without the researcher intervening in their behavior or treatment.
Observational studies and surveys help researchers to study issues where it is neither ethical nor feasible to manipulate the variables. These studies can draw conclusions about potential relationships or associations by carefully measuring and comparing outcomes between different groups.
In summary, clinical trials actively assign interventions and measure results, whereas cohort and other observational studies follow natural outcomes without direct intervention.