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 All the following statements concerning meta- analysis are true EXCEPT. and explain in detail?
Meta-analyses combine results from several studies and, through statistical methods, calculate an overall estimate of effect. Ecological studies use data based on groups of people rather than individuals. Associations observed on an aggregate level may not represent associations on an individual level (ecological bias or ecological fallacy).