The problem with self selection in research is that it makes it makes causal interpretations difficult.
This is a type of bias that occurs often times in social science research. In this type of bias, the respondents cause it because they are totally allowed to decide things for themselves.
The respondents are left to decide for themselves whether they want to participate in the research or not.
Read more on self selection here:
https://brainly.com/question/25261401