Interview is a qualitative approach while the survey questionnaire design is a quantitative approach. Using both interviews and questionnaires means you are conducting mixed-method research. Now, to answer your question: Interview questions are open-ended questions while questionnaires have closed-ended questions. Interview questions require a detailed response (and the questions usually start with what? or How?). While the responses to questionnaires are fixed. For your questionnaire, you could use the Likert scale which uses strongly agree (5 points), agree (4 points), neutral (3 points), disagree (2 points), and strongly disagree (1 point). Search for templates of questionnaires on Google.

Assuming that you are collecting both qualitative (interview) and quantitative (questionnaire) data, then this is an issue about "mixed methods research" designs. One possible use of mixed methods design examines "convergence," with the goal of addressing the same research question with two different types of data. Although this idea can sound appealing, you need to ask yourself why you would want to answer the same question twice? In particular, doing so requires more than twice as much work because you need to collect both types of data and "integrate" the results.

In practice, integrating qualitative and quantitative results can be quite difficult, which may be one of the reasons why you made your original instruments so similar. In other words, if they do exactly the same thing, then they should produce similar results. But in practice, this approach almost always forces the open-ended qualitative interview format into a survey-like set of fixed questions.

If your goal truly is to find out if the two different methods converge on similar results, then you could consider doing a content analysis of the qualitative data, based on the contents of the survey. In other words, start with the content of the survey items as a "codebook" and then use that template as a starting point for analyzing the qualitative data.

Alternatively, if your goal is to use the most effective combination of qualitative and quantitative data, then I would recommend a mixed methods study based on an "explanatory sequential" design. In that case, you begin with your survey questionnaire, and once you the results from that, you pursue them in more depth with a follow-up qualitative study. In this case, the goal is to help understand (i.e.,, explain) the quantitative results.

Really good question! So making the questionnaire questions distinct from the interview questions is all about collecting different kind of data to answer the same or a slightly different research question on the topic. Without getting into methodologies, a rule of thumb I give my students is to DESIGN for OPEN and CLOSE after you interview. First, conduct interviews with experts (or participants who are the most relevant informants), as they will help with finding the real issues. So you may repeat some of the questions in the questionnaire but this time, you know how to 'close' (ie provide answers to tick ) them so they are going to be giving you a 'vote' (frequencies)on the topic rather than in depth answer. When you pilot your questionnaire you will find out which of the questions you can drop. So you interview (thatis use say a handful of questions) and then you make a list of more specific questions on the issues you need a 'vote' on.

Good responses from Bayo, David and Maria. David raises the point of mixed methods - and this would be a serious consideration. That said, I would pass it before AQR first. It may not be what they are after - and then they migth 'drop' the issue of quantifying questions. Jonathon - I note that you say 'answer the research questions' - rather than a single question. Potentially, this might already indicate that you were heading towards mixed methods and, if you did change, certainly would assist.

The clue is to understand what the purpose and function of a questionnaire are? And why a focus group or interviews are needed after or before running a survey. Once you understand the functionality of each, it will be clear for you what you need to do. For example, if we have run a questionnaire, then we discovered that the responses received were more into the neutral aspects or there are details we need to know. Here we have to write a few questions for standardised focus groups or interviews that can help us understand more about these critical areas. We need to see clearly diversity of views and what exactly were the issues behind the responses in the questionnaire that cannot be explained. Therefore, the aims are to get a meaning for what was collected. Also, have some details from participants on specific issues. This is just one example, but there are other reasons.

I recommend reading this book

InterViews: Learning the Craft of Qualitative Research Interviewing Third Edition

by Svend Brinkmann, Steinar Kvale

Jonathon Pawlowski, I hope I have been able to answer your question. And I hope the tips you have gotten so far is enough to help you scale through.

David L Morgan: how about when the purpose of “answering the same question twice” is for completeness, and not convergence?

Completeness is usually summarized as something like QUAN + QUAL so that the qualitative data adds something that would not be available from just the quantitative data itself. In other words, the qualitative data helps "complete" the total data set.

Sekondeko Ronnie Noga, when it comes to answering the same question twice for completeness, it is a technique used in qualitative research. It is member checking and it is very good for ensuring data saturation.

Bayo: is member checking not for improving validity or trustworthiness of findings? If so, how is that ensuring completeness? It seems to fit the purpose of mixed-methods design

Thank you all for the input. However, I realized my error in the question posed. The questionnaire will be an open-ended essay style for a qualitative descriptive study.

Jonathon Pawlowski Following..