A multi-site research study involves conducting research at multiple different locations or sites in order to collect data from a larger and more diverse sample of participants. This approach allows researchers to generalize their findings across a wider range of populations, settings, and conditions. Multi-site research can be especially useful in fields such as public health, education, and social sciences where the findings need to be applicable to a broader audience. It also helps to increase the reliability and validity of the research findings by reducing the impact of individual site-specific characteristics or biases.