The Problem With Survey Non-Response

When you collect the data, if one, for example, individual is eligible and selected into your study, but that individual may refuse to participate. So together, the response rates have become a concern because recently for data collection individuals tended to even know are passed by the survey. But however, response rates are not the only index for non-response bias. Because when we talk about bias, how do the data affect your analysis? And then when we think about the response or non-responsive bias, we have to think about what is the potential bias if you only look at the cases who respond to the data.