You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is To test the association between risk factors and disease, which of the following is the weakest study design? and explain in detail?
Ecological studies, as they donot take into consideration individual data of exposure & diseases, have poorest evidence of determining association. Hence they are considered as weak studies. These are done at point of time & commonly used in nutritional surveys. Order from strong to weak study determining association:Randomized Control Trial > Retrospective Coho Study > Prospective Coho Study > Case control study > Cross sectional study > Ecological study.