"I am conducting research on culture shock, and I am utilizing a mixed methods research design that includes both a questionnaire and interviews. I have designed a questionnaire, but I am unsure about the type of questions that should be asked during the interviews. Should I ask the same (or almost the same) questions during the interviews to validate the results of the questionnaire, or should I ask different, more in-depth questions?"
It sounds like your qualitative interviews will follow the survey. In that case, I would recommend a sequential explanatory design, where the follow up helps you understand the results from the primary study (QUAN --> qual).
In general, qualitative researchers don't approve of validation, and there are several other problems with this approach. First, even if you ask "the same" questions, how are you going to compare the numerical responses from the survey with the semi-structured responses from the open-ended interviews? Second, what you going to if the results disagree? Finally, even if they do agree, you will have gone to a lot of effort to answer the same question twice.
If we have gone through to answer the same question twice, one from the survey and another from the interview. It could be useful to find the actual response. Which can't be hidden from the different Response Biases. Am I right or wrong Dr. David L Morgan?
Sudarshan S. The problem here is with the concept of "actual response." The idea that one set of results or the other has be true is exactly why qualitative researchers do not like the concept of validity. So, if the two methods agree, may they just similar results because they both involve interviewing. Or if they disagree, maybe both of them have different "biases." No matter how you look at it, dealing with the degree of agreement between qualitative and quantitative methods is a difficult thing to do.
Qualitative research does not approve of validation. It can only clarify the questions in the quantitative part of the research. It will allow you to dive deeper into some aspects of your questions and you may discover things you had not thought of previously. However, you do not need to go back and ask those questions. I have in the past used qualitative research (interviews or focus groups) to then decide what the broad issues of the questionnaire should be.