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 By which of the following method the incidence of a disease can be calculated? and explain in detail?
Prospective study is the exposure to the risk factor and subsequent health outcomes are observed after the beginning of the study. Incidence can be calculated by this study. Ref: Park's Textbook of Preventive and Social medicine, 19th edition, Page 71, 74.