In think that what gives "meaning" to a methodological choice is the consensus of the research community, rather than any abstract philosophical position on ontology and epistemology. If your colleagues agree that you are asking a worthwhile question, and that your methods will provide an acceptable answer, then that is all you need.

Article More Than Method?: A Discussion of Paradigm Differences With...

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As the field of mixed methods research has evolved, it has moved away from concerns about ontological and epistemological assumptions. In particular, that approach was developed in the 1980s by qualitative researchers such as Lincoln and Guba, long before mixed methods became a widely accepted option.

Because most advocates for starting with ontology and epistemology teated qualitative and quantitative methods as belonging to different paradigms that cannot be mixed, this did not fit well with mixed methods.

As an alternative, most versions of mixed methods researchers prefer to concentrate on matching the research questions to a set of methods that can address that question in a meaningful way.

It sounds like you are doing mixed methods. I think Crotty 1998 gives a really good explanation of ontology/epistemology and metaphysical debates. It's kind of old now but easy to read and understand.

Creswell & Creswell 2019[?] might be a good one for researching your case study method.

Methodology and its related methods usually follow an already decided ontology and epistemology. While mixed methods usually fit into research premised on a relativist/interpretivist ontology with the related subjectivist or participatory epistemology, they can also be found in research premised on a realist ontology with its objectivist (white coat) epistemology. Research into finding vaccines and cures for Covid 19 will be of the latter kind, while research inquiring into how people have responded and coped with Covid 19 will be of the latter. There may well be some 'Covid 19' research which straddles both.

Let me say that philosophers disagree over almost everything... I still distinguish between Physics (science) and Metaphysics (above science). There are two branches of Metaphysics: Epistemology (knowledge) and Ontology (things). Thus the basic question is how does knowledge relate to things in the the world. Monists argue that there is one basic unit of reality. Materialists argue that things are comprised of matter. Idealists argue that things are ideas. Some are mind-body dualists. Realists argue that Truth is a correspondence between belief and things (material or ideational). Antirealists argue that Truth is socially constructed by powerful groups (scientists) to advance their own interests. Lots more...if you're interested.... especially systems theory.... microcosm v. macrocosm....

As I see it, there should be a relation among the various research tools. The research itself must have unity of intention. This unity, as proposed by the researcher is the gravity center for the use of various or different "methods" or tools. This perspective, as built by the researcher is the element that alows the existence of the epistemology and onthology unity. This point, and its possibility, depends upon the object of research and its scientific area.

Okay, it is from there that meaning is given to the methodological choice

In think that what gives "meaning" to a methodological choice is the consensus of the research community, rather than any abstract philosophical position on ontology and epistemology. If your colleagues agree that you are asking a worthwhile question, and that your methods will provide an acceptable answer, then that is all you need.

Proper description of your epistemology and ontology is well enough to motivate your research design.

I suggest you read more about these concepts in order to have a clear direction and motivation for your research.

Angela,

mixed methods today usually refers to the use or 'mixing' of both quantitative and qualitative methods; however, mixed methods can also be QUAL-QUAL or QUANT-QUANT; thus, whether you case study is qualitative or quantitative (together with your multiple regression) you're doing mixed methods.

That said, and noting David's contributions above, the ontological and epistemological assumptions of your research (which, in my opinion, no research can actually be devoid of) will depend on whether your case study is qualitative or quantitative.

If I try to set myself to the position of a researcher who faces the need (or challenge) to formulate her project's explicit positions on ontology and epistemology, I would be in need for a tentative framework to be developed further for my specific needs.

On the other hand, I have seen examples on ritualist forms, which look like the author had just copied certain phrases without practically any personal contributions.

I have to confess here, that one of the most scaring situations during my public defence would have been if the opponents had asked about details of my project's positions. I tried to formulate them clearly, but I was not satisfied at all and had feelings of inexperience.

Angela, I apologize for coming late to this discussion; I just saw it referenced on another discussion.

If by "case studies" you mean qualitative case studies, and if you're integrating the results of the two methods rather than keeping them separate, you've doing mixed method research.

There are many different ontological and epistemological positions that are compatible with mixed methods research, rather than a single "paradigm" that characterizes the field. See the attached paper.

Angela, each study would have to address the issues associated with a given/constructed or externally-accepted existence of reality of the world (ontology) and how we develop some knowledge, understanding or appreciation of that reality (i.e. our contribution to knowledge generation). What is of vital importance is whether the methods, techniques and tools used to arrive at the ontological and epistemological positions are understandable enough from the point of view of the research participants who provide valuable insights towards that reality and knowledge generation process. If the latter is the case then a certain level of reliability and validity can be ascribed to the findings u=but on the proviso that some degree of triangulation has also taken place and some level of testing has also been conducted. Interesting stuff.

Angela, I disagree with John Mandy's apparent claim that your "methods, techniques and tools" [are] "used to arrive at the ontological and epistemological positions" that you hold, or that the latter need to be "understandable . . . from the point of view of the research participants." Your ontological and epistemological views influence (not determine) your methods, not the reverse. In addition, neither of these need to be understood in detail by the participants in order for your results to be reliable and valid. (For a probably too detailed discussion, see the attached paper "Validity and reliability of research.") What IS important is that your participants understand what you plan to do with your data, and what possible consequences this might have for them (e.g., confidentiality).