How do I choose a theoretical framework for my thesis?

The test to apply is functional. Take your research question and ask what the framework tells you to do that you would not otherwise do. A good framework identifies the variables or categories that matter, rules some explanations out, and gives you a vocabulary shared with the people who will read the thesis. If you can remove it from the methods chapter and nothing changes, it was never load-bearing.

Frameworks chosen for the wrong reasons are easy to spot in a viva. The most common wrong reason is familiarity, adopting the theory your department uses because everyone does. The second is prestige, adopting a difficult framework to signal sophistication. Both produce a chapter that describes the theory at length and then never uses it again.

Work from the question outwards. Look at what the studies closest to yours used, and at what they said about its limits. If three of them note that the dominant framework cannot account for something you care about, that is both your framework decision and a piece of your gap statement.

Settle your epistemology before you settle your framework. Coates and colleagues set out the order as research question, then conceptual framework, then study methods, then data collection, followed by coding, saturation, interpretation, and conclusions, and they ask researchers to state their position first: positivism treats data as absolute, postpositivism allows interpretation of ostensibly absolute data, and constructivism treats reality as produced socially through differing viewpoints (Coates et al., 2021, p. 2). Write down what kind of knowledge your question requires, then check whether the candidate framework's assumptions permit a claim of that kind.

Use the literature review to name the specific problem the framework has to solve. Pautasso argues a review should not be stamp collecting, and should instead identify methodological problems, major debates, and outstanding questions (Pautasso, 2013, p. 3). Pautasso also warns that a gap you claim can go stale, because papers in press or older studies you overlooked may already cover it (Pautasso, 2013, pp. 3-4). His advice comes from roughly 25 reviews written as a PhD student and postdoc rather than from a controlled comparison, so treat it as guidance on practice, not a measured effect (Pautasso, 2013, p. 1). Compare your candidate frameworks against that named problem, and check the comparison again before you fix your choice.

Then read the critics. Every framework has a literature attacking it, and knowing that literature is the difference between adopting a framework and being able to defend adopting it. An examiner will ask why you chose this one over the obvious alternative, and the answer needs to show you knew there was an alternative.

Check the granularity of the categories against your actual data, not against the framework's description of itself. In a study of childhood vaccination barriers, Bonner and colleagues sorted 583 descriptions of implementation barriers into 74 barriers and seven categories inductively, and coded deductively with 84 theoretical constructs across 14 Theoretical Domains Framework domains and six COM-B components, reaching 89% agreement at the domain level on the initial mapping (Bonner et al., 2021, p. 1). Only 10 of the 14 domains were clearly identifiable in their data, and some, such as Environmental Context and Resources, were too broad to separate one type of barrier from another (Bonner et al., 2021, p. 4). A framework can cover your territory and still fail to distinguish the things your question names, so pilot-code a small sample before committing.

What is the difference between a theoretical and a conceptual framework?

A theoretical framework is an existing body of theory you adopt, with its own literature and critics. A conceptual framework is the specific model you build for this study, often drawing on several theories, showing the concepts and the relationships you will examine. Many theses need both.

The conceptual framework is where your own thinking becomes visible. It usually appears as a diagram plus a page of explanation, and it should map onto your research questions closely enough that a reader can see which arrow each question is asking about.

Disciplines use the terms inconsistently, so check what your department expects before writing either. Some fields treat them as synonyms, others require both under those exact headings.

Can I use more than one framework?

Yes, if they answer different parts of the question and you can say how they fit together. Two frameworks with incompatible assumptions about what counts as knowledge will produce a thesis that argues with itself. Check their underlying commitments before combining them, not after.

The compatibility question is about epistemology rather than subject matter. A framework that treats meaning as socially constructed and one that treats behavior as objectively measurable can sometimes be combined in a mixed methods design with careful framing, and cannot simply be stacked.

Bonner's results do not show that one approach is better in every case. Their inductive categories represented the vaccination evidence more clearly and separated barriers better, while the deductive domains that went missing in the data still flagged further issues worth investigating, and they warn that behavioural frameworks can define internal motivation more sharply than external or physical opportunity, which underplays practical implementation problems (Bonner et al., 2021, p. 2). They recommend a hybrid of the Theoretical Domains Framework plus a broader framework because the combination produced a fuller barrier list than either alone, and note that the theory-driven coding alone took about two weeks for two researchers already fluent in those frameworks (Bonner et al., 2021, p. 7). Estimate that extra coding time before you promise two frameworks in a proposal.

When you do combine, write one paragraph stating explicitly what each framework contributes and where the boundary between them falls. That paragraph is the one an examiner will test, and having written it in advance is worth more than any amount of general reading.