Reflecting on the importance of theory-informed qualitative research in people with chronic respiratory disease and their carers

Theory can be defined as “a formal logical explanation of some events that includes predictions of how things relate to one another.”1 Theory can be used in research in many ways. It can be used to help craft, develop, and guide research questions. It can help decide what data you want to capture. It aids in the interpretation and analysis of findings, and it can help to explain the phenomena of interest.2 Often, theories pertain to how people act and behave in certain ways, how a society works, and how businesses and organisations run. Indeed, there are multiple theories which can generate confusion and uncertainty in how to apply theory to research. The consideration of theory is important, particularly at an early stage in research.3 This is to help give research a clear direction. Whilst theory can be applied both a priori and retrospectively, it is the conscious choice – at the outset – that is important. Theory helps guide research, can underpin methodology, and can help understand what is already known on the topic.4 There are two main types of theories, which although distinct, are complementary: explanatory and change theory. Explanatory theories (e.g., health belief model) seek to explain why a person acts or feels a certain way. Whilst important this information isn’t enough to promote a change in behaviour to improve that persons’ health which is why the application of a change theory is also necessary (e.g., transtheoretical model). Both types of theory – explanatory and change theories – can be used in qualitative research. Explanatory theory can guide the methodology, for example, guiding interview research questions to focus on the explanation of a particular phenomenon and/or providing the structure to a framework which can be used in thematic analysis of interview data. Change theory can also be applied in a similar way. For example, in designing a qualitative evaluation of a service to understand ‘what works’. Additionally, it can be used alongside other methods to qualitatively explain what is going on; for example, understanding the causal mechanisms that may be ‘in play’ in a randomised controlled trial.5