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From theory to practice: applying COM-B & TDF in qualitative analysis
Frameworks like COM-B and the Theoretical Domains Framework (TDF) offer structured ways to understand behaviour, but their application in qualitative analysis can be far more complex than expected.
While these models categorise behaviour into elements like Capability, Opportunity, and Motivation, applying them in real-world contexts requires more than just understanding the theory. The challenge lies in accurately diagnosing what truly drives behaviour—especially when using qualitative data, where behavioural influences often overlap and appear in subtle, nuanced ways.
Unlike traditional methods such as thematic analysis, which codes for general themes, frameworks like COM-B and TDF demand precision in identifying specific behavioural constructs. A small misstep in coding can lead to interventions that target the wrong barriers, wasting resources and potentially reinforcing the behaviours you aim to change.
This article will explore:
The unique challenges of using behavioural frameworks in qualitative research
Why practical experience is essential for accurate behavioural diagnosis
Common pitfalls in coding and how they affect intervention outcomes
Every project is different
The complexity of applying behavioural frameworks like COM-B and TDF shifts depending on the behaviour being studied. For example, the way people talk about public versus private behaviours can differ significantly. With more private behaviours, emotions and personal factors often cloud the responses, while public behaviours tend to be shaped by external influences, like social pressure.
Linguistic patterns also change based on both the target audience and the behaviour in question. When the topic is emotionally charged, responses become more layered, making it harder to pinpoint the underlying influences. If the behavioural scientist wasn’t involved in designing the discussion guide, it can be even tougher to gather the insights needed for accurate coding, adding yet another layer of complexity to the process.
In addition to the varying complexity of behaviours, several factors make coding and behavioural diagnosis more challenging:
Self-awareness and knowledge: People often aren’t fully aware of why they behave in certain ways. It’s up to the practitioner to detect those unspoken or subconscious influences that may not be immediately obvious.
Honesty: Respondents may avoid the truth—not out of dishonesty, but due to self-deception or feelings of shame. Behaviours that are embarrassing or socially frowned upon may be downplayed or left out entirely.
Memory and recall: Even when people are self-aware and willing to be honest, they might not accurately recall why they acted a certain way, further complicating the diagnosis.
These barriers can distort the insights gathered, especially when combined with the nuances of context. Every project brings its own set of challenges, whether it’s the nature of the behaviour itself, the emotional charge of the topic, or the limitations of human memory and honesty. This makes a flexible and insightful approach essential for producing accurate behavioural diagnoses and effective interventions.
The distinct approach of coding in behavioural frameworks
Coding within frameworks like COM-B and TDF requires a more structured approach compared to traditional qualitative methods like thematic analysis or grounded theory. Instead of drawing themes from the data, practitioners have to fit the language used into predefined categories—like beliefs, attitudes, or self-regulation—which demands a high level of precision when translating real-world expressions into specific behavioural constructs.
Data doesn’t always fit neatly into one category because a single sentence might touch on several factors—such as capability, opportunity, and motivation—which complicates the coding process. When a single sentence gets coded across three or more TDF domains, it can blur the analysis and dilute the clarity of the insights. This becomes particularly important when barriers and facilitators are discussed within the same context, as coding them together can make the final interpretation less clear.
Beyond the coding itself, there’s a need to think ahead to how the data will be analysed. Applying multiple domains to a single statement can make it harder to keep the analysis focused. If the distinctions between barriers and facilitators aren’t kept clear, there’s a risk that the insights will be lost in the complexity, making it harder to produce actionable outcomes.
There’s no manual or glossary that tells you exactly how people describe their behaviours. Each project presents its own challenges, and over time, practitioners develop their own mental glossary to make sense of these subtleties. While training materials often simplify examples to make them clearer, real-world data is rarely so clean. The real skill in applying COM-B and TDF lies in navigating these messy, real-world contexts, and this level of skill only comes with practice and experience working with complex data.
The role of expertise in behavioural diagnosis
Understanding concepts like self-efficacy and social influences is one thing, but spotting them in everyday conversations is another. People rarely speak in theoretical terms—no one says, "I have low self-efficacy." Instead, they describe their feelings or behaviours in ways that require you to read between the lines.
Those with more experience tend to pick up on these patterns more quickly and with greater accuracy, especially when behavioural influences overlap or interact in complex ways. Early on in my work with the Theoretical Domains Framework (TDF), I struggled with this. But after coding over 200 interview transcripts, I’ve learned how familiar these patterns can become over time. That said, they’re never static—they shift with context, whether the behaviour is public or private, or influenced by emotional factors.
Experienced practitioners also develop the ability to pick up on subtle language cues and tell apart overlapping concepts, like social norms versus group identity. This kind of nuanced understanding leads to more accurate diagnoses and ultimately better interventions.
Common analysis mistakes and their consequences
When applying behavioural frameworks like COM-B or TDF, mistakes in the analysis can lead to interventions that fail to address the real barriers to behaviour change. These mistakes generally fall into two main categories: misclassifying the source of influence and failing to accurately differentiate between TDF domains or constructs. Additionally, a related challenge is disentangling overlapping influences, which complicates both the coding and analysis.
I will use examples from one of my projects that focused on vaccine hesitancy among caregivers in sub-Saharan Africa and specifically the barriers to childhood vaccination to make these analysis challenges more tangible. Detailed summary tables can be found at the end of the post!
Misclassifying the source of influence
One common error is misclassifying whether a barrier is internal or external. For example, a barrier might be rooted in an individual’s internal beliefs (such as self-efficacy) or due to external factors (such as physical opportunity, like logistical access).
If a barrier is misidentified, the intervention may focus on the wrong driver. Addressing a psychological barrier (e.g., building confidence) won’t help if the true issue is an external constraint like transport. Conversely, solving logistical challenges won’t address an internal lack of confidence. These missteps lead to interventions that are misaligned with the actual problem, reducing their effectiveness.
Not differentiating accurately between TDF domains and constructs
The TDF includes 84 constructs organised into 14 domains. Correctly identifying the domain is important, but misidentifying the specific construct within a domain can be just as problematic because it leads to interventions that fail to address the true behavioural barrier.
For example, if you confuse social norms with group identity, you might design a public messaging campaign based on changing descriptive norms. However, if the issue is deeply rooted in group identity, this campaign could fall flat because it doesn’t address the deeper cultural or identity-based concerns. Conversely, if you assume group identity is the problem when it’s really about social norms, a targeted approach using local influencers could have been more effective.
Social Norms: If a caregiver talks about what others in their community typically do regarding vaccination, they might be referring to descriptive norms (i.e., "People around here don’t usually vaccinate their children"). Alternatively, they might mention injunctive norms, which are what they believe others think they should do (e.g., "People in my village expect us not to trust vaccines"). The correct intervention would focus on changing perceptions of what others do or expect. A behavior change technique (BCT) might involve normative feedback or public commitment—interventions that leverage social proof to shift perceptions of what is normal and expected within the group.
Group Identity: On the other hand, if the caregiver refers to their identity as part of a group that historically resists foreign medical interventions (e.g., “We are proud of our traditions and don’t trust Western medicine”), this would be better coded under group identity. Here, the intervention would need to appeal to group belonging and identity. A suitable BCT might involve working with respected community leaders to influence the group’s sense of identity around health behaviors, or promoting ingroup models who exemplify vaccination in a way that aligns with cultural values.
Disentangling contradictory and overlapping influences
When analysing behaviour, both barriers and facilitators often appear within the same statement, and it’s not always clear whether one factor is a cause or consequence of another. Disentangling these overlapping influences is key to identifying the true drivers of behaviour and developing effective interventions. Key considerations include:
Multiple influences in one statement: A single response may contain both barriers and facilitators, making it necessary to separate the positive and negative drivers.
Cause vs. consequence: It's crucial to determine whether one influence is the cause or consequence of another, helping identify the primary driver and its connections.
Misclassification of influences: Confusing a facilitator for a barrier (or vice versa) can lead to incorrect coding, skewing analysis and leading to ineffective interventions.
Interaction of influences: Understanding how internal (e.g., self-efficacy) and external (e.g., logistical access) factors interact is critical for accurate analysis.
Incomplete interventions: Addressing only barriers or facilitators, without considering both, can result in partial solutions that overlook key influences.
Comprehensive coding: Coding should capture both barriers and facilitators, and clarify their interaction and role (cause or consequence) in shaping behaviour.
Summing up: the art of behavioural diagnosis
Ultimately, success in behavioural diagnosis relies on the combination of solid theoretical knowledge and hands-on experience. While behavioural frameworks like COM-B and TDF provide a structured approach to understanding behaviour, applying them in real-world contexts is far from straightforward.
The theories themselves may seem simple, but the actual process of diagnosing behaviour is nuanced and requires practical experience. The ability to read between the lines, spot subtle cues, and navigate overlapping influences comes from experience—making the role of expertise critical in achieving effective behavioural diagnosis because mistakes at this foundational stage of the behaviour change process can lead to ineffective interventions that target the wrong barriers.
In practice, it’s this deeper understanding of psychological principles and the experience to apply them correctly that separates successful interventions from those that fall short.
Detailed example of misclassifying the source of influence
Emphasis on... | "I’m not sure if I can manage to get my child to the clinic on the right day." | "The clinic is so far away, and I don’t think I can get there." |
Type of concern/ interpretation | The individual doubts their personal ability to take the required action (self-efficacy) | The individual is primarily facing environmental barriers—their concern is about their physical environment (the distance to the clinic) and not necessarily about their own abilities. |
Relevant TDF domain and construct | Beliefs about Capabilities: Self-Efficacy | Environmental Context and Resources (no need to go into the constructs here) |
Intervention Strategy: | Build self-efficacy:
| Increase Physical Opportunity:
|
Consequence of miscoding | If the problem is actually related to physical opportunity (e.g., the distance to the clinic), but the intervention focuses on building self-efficacy, you might offer the caregiver confidence-building tools or reminders, but that wouldn’t address the actual environmental barrier. As a result, the caregiver still won’t be able to get to the clinic due to external factors, and the intervention would likely fail. | Conversely, if the caregiver lacks confidence in their own ability to organize and manage the trip, but the intervention focuses on logistical support (e.g., providing transport), you might offer transportation services, but the caregiver’s underlying lack of confidence remains unaddressed. They might still not go because they doubt they can follow through with the task, even with the help. |
Detailed example of not differentiating accurately between TDF domains and constructs
Interpretation | People around here don't usually vaccinate their children. | We are proud of our traditions and don't trust Western medicine. |
Type of concern | Perceptions of what others do (descriptive norms) or what others think they should do (injunctive norms). | Sense of belonging to a group that holds shared values or beliefs about resisting foreign interventions. |
Relevant TDF domain (code) | Social Norms | Group Identity |
Intervention Strategy | Focus on changing perceptions of norms through normative feedback or public commitment. Leverage social proof to shift expectations within the group. | Focus on appealing to group belonging and identity. Engage respected community leaders or use ingroup models to exemplify health behaviors in line with group values. |
Consequence of miscoding | If coded as group identity, normative interventions might fail to change behavior because the deeper identity-based concerns aren't addressed. | If coded as social norms, interventions targeting group belonging might fail if the real issue is a misunderstanding of what others expect or do. |
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