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 Which is most economical and best screening and explain in detail?
Ref:Parks 23rd edition pg 137 High-risk or selective screening : Screening will be most productive if applied selectively to high-risk groups, the groups defined on the basis of epidemiological research. Types of screening : Mass screening. High-risk or selective screening. Multi-phasic screening.