I have recommended something similar in the attached paper. I myself would not call this mixed methods, however, because there is only one data source.
Article Qualitative Content Analysis: A Guide to Paths Not Taken
The important focus here is the research question and what method would best answer this question. This should guide your approach. It also means that you have to have rich data in order to generate trustworthiness and reliability of data so spend some time ensuring you have developed rigorous data collection processes.
I think triangulation, as it's called in some fields, is a good way to question the validity of our results, because inevitably the "same" question asked qualitatively and quantitatively won't give you the same answer. It keeps you from falling into the "eureka" trap, i.e. thinking you've found it all, as we sometimes do... I have quite a few references on the subject, if you want. For instance Netanda 2012, Mertens & Hesse-Biber 2012, Rheinländer 2011, Teddlie & Tashakkori 2003, Denzin 2012... If you need more precise references, tell me.
All of the versions of triangulation that I know require the independent collection of both qualitative and quantitative data. Doing both qualitative and quantitative analysis of the same data would not meet the usual definition of triangulation.
For stylistics, its a good idea to triangulate data based on content analysis and textual analysis which will surely validate your data and consider it reliable in relation to your research objectives.
Adevanju, There is crucial to determine in what stage of your study you really want to combine? But what I suggest is that; definitely, you would coming up with some results from your quantitative content analysis part. Similarly, you would have findings from your qualitative part. Now; you may want to integrate your results of the quantitative part with your findings from your qualitative investigation in the discussion section of your study in order to corroborate the consistency of your results and findings from Qual. and Quan., which complement your outcomes. As the results, you will find out if there is any consistency with the body of your literature to suggest a general confirmation of your hypotheses or proposition as well.
There is really nothing that speaks against. The question is why combine. The theoretical starting point plays a central role. From a more social constructionist perspective, keep in mind that the results are not "more true" using mutiple methods. This requires, however, arguments for the choice of combination.