Not all qualitative work is exploratory, so you definitely can use qualitative methods to assess or evaluate the predictions of an existing theory. I personally would avoid the word "test," because it is so associated with tests of statistical significance. In particular, it rare for qualitative observations to generate enough data to do meaningful statistical analyses.

I think that an embedded design would be the best for your work, (i.e., testing an existing theory), which means that a qualitative research component is included within a larger, quantitative study.

Thanks David and Claire! Further I would like to know, if I am using qualitative methods of data collection, how to maintain the quality of research(validity-reliability or credibility of research)

There has been a large discussion of "credibility" in qualitative research, starting with Lincoln & Guba's introduction of this term in their book, Naturalistic Inquiry. Their goal was to provide an alternative to the more quantitatively oriented concepts of reliability and validity.

Others, however, argue that reliability and validity are useful standards for qualitative research, e.g. Morse et al. (2002) "Verification Strategies for Establishing Reliability and Validity in Qualitative Research" in International Journal of Qualitative Methods.

It can be subject to validity for context

In addition to the 2nd answer of David L Morgan , I would suggest that you first choose the data collection method (for qualitative research) and then look into the literature that (possibly) instructs on improving the trustworthiness of the method used and its respective analysis. Or, check the articles of the top journals of your field that have used the same data collection method, how have they ensured the credibility of their study/work.

A lot will depend upon the nature of theory and level of abstraction. Most middle-ranged or more specific theories consist of testable interrelated assumptions (e. g. , Lee’s Theorynof Migration) consist of relationships between quantifiable constructs/variables. To test those theories, quantitative data will be more appropriate. If the idea is to form theories and hypothesis, qualitative research (inductive reasoning) will be appropriate.

I'd second the suggestion of avoiding the word "test" as to test something you have to have a control - and in qualitative research the objective is usual phenomena that can't be controlled, like meaning and unintended consequences of action, because that's what makes them interesting. In other words, the problem is epistemological incompatibilty as you are generating a type of knowledge that may be credible and vaild, and may lend that credibility to a theory or set of theories as an account, but is context dependent. And for most social theories, if you control the environment (as in lab group experiments) you dilute the social dynamics and find problems and inconsistencies applying findings to the field.

The impact of any theory can be assessed by using different techniques that represent it then to assess the results of applying these techniques. So, you can use the aforementioned measurement tools to assess the manifestation of the theory.

Liqaa

Qualitative research has numerous strengths when properly conducted .

Thanks everyone for your valuable comments. Any references to cite for use of qualitative methods of data collection for evaluating theory?

Thanks Britton