Choosing the right theory is one of the most important decisions in academic research. A theory gives your study an intellectual foundation. It explains why your variables, concepts, relationships, or research problem matter. Without a suitable theory, a study may become descriptive, weakly justified, or disconnected from existing scholarly debate.

In a PhD thesis, proposal, or empirical paper, theory is not simply something added to make the study look academic. It should guide the research problem, support the research gap, justify the conceptual framework, inform the hypotheses or research questions, and help interpret the findings. Varpio et al. explain that a theoretical framework is not merely the name of a theory; it is the logical use of theory to scaffold and support a particular study. (PubMed)

What Is a Theory in Research?

A theory is a structured explanation of a phenomenon. It usually consists of concepts, assumptions, propositions, and relationships that help explain, predict, or interpret social, organisational, behavioural, educational, or economic realities.

For example, the Theory of Planned Behaviour explains how attitude, subjective norms, and perceived behavioural control influence behavioural intention. The Technology Acceptance Model explains why individuals accept or reject technology. The Resource-Based View explains how internal resources can create competitive advantage. Institutional Theory explains how organisations respond to formal and informal pressures in their environment.

In simple terms, theory helps answer this question:

Why is this phenomenon happening, and how can it be explained academically?

Start with Your Research Problem

The first step in choosing a theory is to understand your research problem clearly. Many students make the mistake of selecting a popular theory before they fully understand what their study is actually investigating.

For example, if your study is about teachers' adoption of AI-based learning systems, your research problem is related to technology acceptance, readiness, trust, digital literacy, and institutional support. Therefore, suitable theories may include the Technology Acceptance Model, UTAUT, Diffusion of Innovation Theory, or Social Cognitive Theory.

However, if your study is about SMEs' performance and competitive advantage, the problem is more related to organisational resources, capabilities, strategy, innovation, and market competitiveness. Suitable theories may include the Resource-Based View, Dynamic Capabilities Theory, or Contingency Theory.

The key point is that the theory must fit the research problem, not the other way around.

Match the Theory with Your Main Constructs

A good theory should explain the major constructs or variables in your study. If the theory cannot explain your key variables, it is probably not suitable.

For example, suppose your study examines:

Digital literacy → Teacher readiness → AI adoption

A technology adoption theory can explain the adoption outcome, but it may not fully explain digital literacy or teacher readiness. Therefore, you may need to combine it with another theory, such as Social Cognitive Theory, if self-efficacy and capability are central to the study.

Another example:

Leadership style → Job satisfaction → Employee performance

Here, Social Exchange Theory may be suitable because it explains how employees respond positively when they perceive support, fairness, or quality leadership. If the study focuses on motivational mechanisms, Self-Determination Theory may also be relevant.

A theory should not be chosen only because many previous studies used it. It should be chosen because it explains your variables and relationships logically.

Check Whether the Theory Supports Your Research Objectives

Your theory should align with your research objectives. If your objective is to examine relationships between variables, the theory should support those relationships. If your objective is to explore experiences, the theory should help interpret those experiences.

For a quantitative study, the theory often supports hypotheses. For example:

• Research Objective: To examine the effect of perceived usefulness and perceived ease of use on students' intention to use e-learning platforms.
• Suitable Theory: Technology Acceptance Model.
• Reason: TAM directly explains how perceived usefulness and perceived ease of use influence behavioural intention to use technology.

For a qualitative study, the theory may act as an interpretive lens. For example:

• Research Objective: To explore Indigenous school leaders' culturally responsive leadership practices.
• Suitable Theory: Culturally Responsive School Leadership framework.
• Reason: The theory helps interpret how school leaders respond to students' cultural identities, community values, and educational needs.

Look at Previous Studies in Your Field

A practical way to choose a theory is to review recent and high-quality studies in your research area. Look at which theories have been used, how they were applied, and what limitations previous authors identified.

However, you should not simply copy the theory used by previous researchers. Instead, ask:

• Why did they use this theory?
• Did the theory explain the phenomenon well?
• Did the authors suggest theoretical limitations?
• Is there a need to extend, combine, or challenge this theory?
• Are there newer theories or alternative perspectives?

Whetten's classic article on theoretical contribution is useful here because it explains that theory involves more than listing variables; it requires explaining what factors are involved, how they are related, why the relationships exist, and under what conditions they operate. (Wikipedia)

Choose a Theory That Explains the "Why"

A theory is valuable because it explains why a relationship or phenomenon exists. A weak theoretical framework only says:

This study is based on the Technology Acceptance Model.

A stronger theoretical framework says:

This study is based on the Technology Acceptance Model because the model explains how users' perceptions of usefulness and ease of use shape their intention to accept technology. Since the present study examines teachers' intention to adopt AI-based learning systems, TAM provides a suitable theoretical foundation for explaining technology acceptance behaviour.

The second version is stronger because it connects the theory directly to the study.

Sutton and Staw's influential discussion of "what theory is not" is often cited because it reminds researchers that references, diagrams, variables, and hypotheses alone do not constitute theory. A theory must explain the logic behind relationships, not merely name the components of a model.

Consider the Level of Analysis

The theory must match the level of your study. Some theories explain individual behaviour, while others explain organisational, institutional, or societal phenomena.

For example, if your respondents are individual employees and your outcome is employee performance, individual or organisational behaviour theories may be suitable, such as Social Exchange Theory, Self-Determination Theory, or Job Demands-Resources Theory.

If your unit of analysis is the organisation, such as SMEs or universities, theories such as Resource-Based View, Dynamic Capabilities Theory, Institutional Theory, or Contingency Theory may be more appropriate.

If your study examines national-level readiness, such as CBDC readiness or financial inclusion, Institutional Theory, Technology–Organisation–Environment framework, or Financial Inclusion Theory may be more suitable than individual-level behavioural theories.

A common mistake is using an individual-level theory to explain an organisational-level outcome without justification.

Decide Whether You Need One Theory or Multiple Theories

Some studies can be adequately supported by one theory. Others require more than one theory because the research model includes different types of variables or mechanisms.

For example, in a study on AI adoption among teachers, TAM may explain technology acceptance, while Institutional Theory may explain how school support, policies, and organisational readiness influence adoption. In a study on SME performance, RBV may explain internal resources, while Dynamic Capabilities Theory may explain how firms adapt those resources in changing environments.

Using multiple theories can strengthen a study, but only when the integration is logical. Do not add theories just to make the thesis look sophisticated. Too many theories can make the study confusing and theoretically fragmented.

A good rule is:

Use one main theory when it sufficiently explains the study. Use multiple theories only when each theory explains a distinct and necessary part of the model.

Check the Theory's Fit with Your Methodology

The theory should also fit your methodology. In quantitative research, theories are often used deductively to develop hypotheses. In qualitative research, theories may be used as sensitising frameworks, interpretive lenses, or tools for explaining emerging themes. In mixed-methods research, theories may guide both measurement and interpretation.

For example, if you are using PLS-SEM to test relationships between variables, your theory should support causal or predictive paths. If you are conducting interviews, your theory should help guide the interview protocol and interpretation of participants' experiences.

Eisenhardt's work on theory building from case study research is important for qualitative and case-based studies because it shows how theory may also emerge from systematic comparison of cases, rather than only being applied before data collection. (Wikipedia)

Make Sure the Theory Supports Your Research Gap

A strong theory choice should help you address the research gap. For example, if the gap is that previous studies examined only direct effects, you may choose a theory that supports mediation or moderation.

Example:

• Gap: Previous studies examined the direct relationship between leadership and employee performance but gave limited attention to psychological mechanisms.
• Theory: Social Exchange Theory or Self-Determination Theory.
• Justification: These theories help explain how leadership affects performance through employee attitudes, motivation, commitment, or job satisfaction.

Another example:

• Gap: Previous studies examined SME resources but did not explain how firms adapt under uncertainty.
• Theory: Dynamic Capabilities Theory.
• Justification: This theory explains how firms sense opportunities, seize them, and reconfigure resources in changing environments.

The theory should not be separate from the gap. It should help solve the gap.

Evaluate the Theory's Scholarly Acceptance

A good theory should be recognised in your discipline. This does not mean it must be old or traditional, but it should have sufficient academic credibility. You should be able to cite foundational works and recent empirical studies that used the theory.

For example, TAM, TPB, UTAUT, RBV, Institutional Theory, Stakeholder Theory, and Social Exchange Theory are widely accepted in many areas of social science. However, even a well-known theory must still be justified for your specific study.

Gregor's work on the nature of theory in information systems is useful because it explains that theories may serve different purposes, including analysis, explanation, prediction, explanation-and-prediction, and design/action. This reminds researchers that the selected theory should match the purpose of the study, not only the topic area.

Avoid Choosing a Theory Only Because It Is Popular

Popularity is not the same as suitability. A theory may be widely used but still inappropriate for your study.

For example, the Technology Acceptance Model is popular in technology studies, but it may be too narrow if your study focuses heavily on institutional policy, ethics, organisational readiness, or cultural norms. In that case, UTAUT, TOE, Institutional Theory, or an integrated framework may be more suitable.

Similarly, the Resource-Based View is popular in business research, but if your study focuses on rapid environmental change, innovation, or adaptation, Dynamic Capabilities Theory may provide stronger explanatory power.

Choose theory based on explanatory fit, not popularity.

Practical Criteria for Choosing a Theory

A suitable theory should meet several criteria. It should explain the main research problem, fit the key variables or concepts, align with the research objectives, support the research gap, match the level of analysis, fit the methodology, and provide a basis for interpreting findings.

You can ask yourself these questions:

If the answer is mostly yes, the theory may be suitable.

• Does this theory explain my main phenomenon?
• Does it justify my independent, dependent, mediating, or moderating variables?
• Does it align with my research objectives and questions?
• Has it been used in similar studies?
• Can it support my hypotheses or interview questions?
• Does it help me interpret the expected findings?
• Does it strengthen my contribution to knowledge?

Example 1: AI Adoption in Education

• Research Topic: AI-based learning system adoption.
• Possible Variables: Teacher readiness, digital literacy, trust in AI, perceived usefulness, institutional support, adoption intention.
• Possible Theories: Technology Acceptance Model, UTAUT, Social Cognitive Theory, Institutional Theory.
• Best Choice: If the study focuses on individual teachers' acceptance, TAM or UTAUT may be suitable. If the study focuses on institutional support and school readiness, Institutional Theory or TOE may be added. If the focus is on teachers' confidence and capability, Social Cognitive Theory may be useful.

Example 2: Employee Performance

• Research Topic: Leadership, job satisfaction, and employee performance.
• Possible Variables: Leadership style, employee engagement, job satisfaction, organisational commitment, employee performance.
• Possible Theories: Social Exchange Theory, Self-Determination Theory, Job Demands-Resources Theory.
• Best Choice: If the study argues that supportive leadership creates positive employee responses, Social Exchange Theory is suitable. If the study focuses on motivation and psychological needs, Self-Determination Theory is more suitable. If the study focuses on work demands and resources, JD-R Theory is appropriate.

Example 3: SME Performance

• Research Topic: Managerial competencies and SME performance.
• Possible Variables: Managerial competencies, innovation capability, competitive advantage, firm performance.
• Possible Theories: Resource-Based View, Dynamic Capabilities Theory, Human Capital Theory.
• Best Choice: If the study focuses on valuable internal resources, RBV is suitable. If it focuses on adaptation, innovation, and changing environments, Dynamic Capabilities Theory is stronger. If it focuses on knowledge, skills, and competencies of managers, Human Capital Theory can support the argument.

Example 4: Environmental Behaviour

• Research Topic: Willingness to pay for ecosystem conservation.
• Possible Variables: Attitude, subjective norms, moral norms, perceived behavioural control, trust, perceived risk reduction, willingness to pay.
• Possible Theories: Theory of Planned Behaviour, Value-Belief-Norm Theory, Norm Activation Model.
• Best Choice: If the study focuses on behavioural intention, TPB is suitable. If it focuses on moral responsibility and environmental values, Value-Belief-Norm Theory or Norm Activation Model may be more appropriate. If both intention and moral obligation are central, an extended TPB model may be justified.

How to Write the Theory Justification

A good theory justification should include four elements: the name of the theory, its main assumptions, why it fits the current study, and how it supports the research model.

Example:

This study is underpinned by the Theory of Planned Behaviour because the model explains how behavioural intention is shaped by attitude, subjective norms, and perceived behavioural control. Since the present study examines local communities' willingness to pay for ecosystem conservation, TPB provides a suitable theoretical foundation for explaining intention-based environmental behaviour. The theory also supports the inclusion of perceived behavioural control and social influence as predictors of willingness to pay.

This is much better than simply writing:

This study uses the Theory of Planned Behaviour.

Common Mistakes in Choosing Theory

One common mistake is selecting a theory after the framework has already been developed. In that case, the theory becomes decorative rather than foundational.

Another mistake is using too many theories without integration. This makes the study look unfocused. The researcher must explain how the theories complement each other.

A third mistake is choosing a theory that does not match the dependent variable. For example, using a technology acceptance theory for a study that is mainly about organisational performance may be weak unless the link is clearly justified.

A fourth mistake is failing to connect the theory to hypotheses. Every key relationship in the conceptual framework should have theoretical or empirical support.

Conclusion

Choosing the right theory requires careful alignment between the research problem, research gap, variables, objectives, methodology, and expected contribution. A theory should not be chosen because it is popular or easy to cite. It should be chosen because it explains the phenomenon and strengthens the academic logic of the study.

A strong theory choice helps the researcher justify the conceptual framework, develop meaningful hypotheses or research questions, interpret findings, and demonstrate contribution to knowledge. In simple terms, the theory is the intellectual foundation of the study. When the theory is well chosen, the entire research becomes more coherent, defensible, and scholarly.

Key References

• Eisenhardt, K. M. (1989). Building theories from case study research. Academy of Management Review, 14(4), 532–550.
• Gregor, S. (2006). The nature of theory in information systems. MIS Quarterly, 30(3), 611–642.
• Sutton, R. I., & Staw, B. M. (1995). What theory is not. Administrative Science Quarterly, 40(3), 371–384.
• Varpio, L., Paradis, E., Uijtdehaage, S., & Young, M. (2020). The distinctions between theory, theoretical framework, and conceptual framework. Academic Medicine, 95(7), 989–994. (Uniformed Services University)
• Whetten, D. A. (1989). What constitutes a theoretical contribution? Academy of Management Review, 14(4), 490–495.