I don't know "INOVA or Bt T test" are, but in general you will not produce measurable data from qualitative interviews. One approach that might accomplish this would be content analysis, where you would count specific elements ("codes") in the interview transcripts.

A different approach would be to follow what mixed methods research would term a "sequential explanatory" method, which can be summarized as QUANT --> qual. The goal in that case would be to establish a set of results using a major quantitative study, and then conduct a smaller qualitative study to understand how and why the results occurred. 

Dear Elhaj,

I would recommend grouping the relevant sections of your interview transcripts according to the scores on the associated Likert scale in question. You can then check for consistency between the Likert scale scores and the verbal descriptions and also form interpretations for the constructs related to each Likert response value.

I don't know "INOVA or Bt T test" are, but in general you will not produce measurable data from qualitative interviews. One approach that might accomplish this would be content analysis, where you would count specific elements ("codes") in the interview transcripts.

A different approach would be to follow what mixed methods research would term a "sequential explanatory" method, which can be summarized as QUANT --> qual. The goal in that case would be to establish a set of results using a major quantitative study, and then conduct a smaller qualitative study to understand how and why the results occurred. 

I used mixed method as explained by David, in which I utilized the qualitative study to explain and explore finding from the quantitative one. If we compare the results, then we will conclude one method is better than the others. Or, we might infer that one method is more reliable. In my case, I avoided such things. Instead, I tried to interpret the phenomena obtained from both methods. I hope it helps you interpreting your results.

Thanks Peter , Davis & Didik for contribution. Moreover, I wanna explain that the interview is closed end questions to evaluate the same indicators of questionnaire.

It sounds like you are using one close-ended questionnaire to validate another close-ended questionnaire. Is that really worth the additional effort?

Some details on your research method is needed, are you going to interview the same people who had already  filled  the questionnaire or different people? if they are different, then the  answers came from two different groups and can't be  compared for consistency, and  if they are the same group it does not worth additional efforts as David said. i agree with David and Didik in that do quantitative study and on the bases of the results you can do some in-depth analysis using qualitative data collected by personal interviews.

the same questions of questionnaires will be conducted to all sample (Quality Managers, Sales and Marketing MGR, R & D MGR, Production MGR, Production Supervisors & Quality team) as self administrated questionnaire.

The same questionnaires will be  used as interview with General MGR and CEO'S to assess whether the questionnaire data is reliable with GMR & CEO'S feedback. 

I hope this clarification makes sense !

This makes sense in the context of quantitative research as a form of test-retest reliability, but I myself would not think of this as mixed methods.

Reliability test is to be done before data collection, take small sample and do test-retest , ie distribute the  questionnaire, fill them and redistribute the same questionnaire to the same people with different interviewers. on the bases of reliability test improve your questionnaire and go to the fiels. But this is not a mixed method as dr. Morgan said.   Mixed method is done if you feel that you need more information based on the results obtained by the quantitative data. you go back to collect more information from informative persons