A recent article in BMJ Quality and Safety offers a lively and useful account of the role of theory in applied research, with examples taken from service delivery research. The authors explain repeatedly that theory is always present when a service is changed, and that the choice lies in making theory formal and explicit versus leaving it vague and implicit. The article covers grand theories (such as the idea of culture); mid-range theories (such as social behavioural theory, which emphasises the effect of social clues on behaviour); and programme theories (which map out the territory between cause [e.g. more nurses] and outcome [e.g. healthier, happier patients]). A detailed discussion of programme theory was recently published by CLAHRC Northwest London.
One of the problems that provokes the CLAHRC WM Director is the observation that the same theory may go under different names (‘the same wine in new bottles’) or that theories may overlap. For example, Ferlie and Shortell, and Richard Grol  have both developed a similar theory (that successful organisational change requires co-ordinated responses from different levels in the organisational hierarchy). Also, in many circumstances, it may be necessary to determine which theories are relevant and which are not. For example, should an intervention be designed according to nudge theory, social behavioural theory, the theory of planned behaviour, or one of the other 64 psychological theories of behavioural change? Here, one turns to a theory of theories – for example, the transtheoretical model. 
— Richard Lilford, CLAHRC WM Director
- Davidoff F, Dixon-Woods M, Leviton L, Michie S. Demystifying theory and its use in improvement. BMJ Qual Saf. 2015; 24: 228-38.
- Reed JE, McNicholas C, Woodcock T, Issen L, Bell D. Designing quality improvement initiatives: the action effect method, a structured approach to identifying and articulating programme theory. BMJ Qual Saf. 2014. [ePub].
- Ferlie EB & Shortell SM. Improving the quality of health care in the United Kingdom and the United States: a framework for change. Milbank Q. 2001; 79(2): 281-315.
- Grol R, Wensing M, Eccles M, Davis D, eds. Improving patient care: the implementation of change in health care. Hoboken, NJ: John Wiley & Sons. 2013.
- Prochaska JO, Velicer WF. The transtheoretical model of health behaviour change. Am J Health Promot. 1997; 12(1): 38-48.
- Michie S, Johnston M, Francis J, Hardeman W, Eccles M. From theory to intervention: mapping theoretically derived behavioural determinants to behaviour change techniques. Appl Psychol. 2008; 57(4): 660-80.