Being realistic about “realist” evaluation


Realist evaluation (formerly known as realistic evaluation; Pawson & Tilley, 2004, p. 3) is an approach to Theory-Based Evaluation that treats, e.g., burglars and prisons as real as opposed to narrative constructs; follows “a realist methodology” that aims for scientific “detachment” and “objectivity”; and also strives to be realistic about the scope of evaluation (Pawson & Tilley, 1997, pp. xii-xiv).

“Realist(ic)” evaluation proposes something apparently new and distinctive. How does it look in practice? What’s new about it? Let’s have a read of Pawson and Tilley’s (1997) classic to try to find out.

Déjà vu

Open any text on social science methodology, and it will say something like the following about the process of carrying out research:

  1. Review what is known about your topic area, including theories which attempt to explain and bring order to the various disparate findings.
  2. Use prior theory, supplemented with your own thinking, to formulate research questions or hypotheses.
  3. Choose methods that will enable you to answer those questions or test the hypotheses.
  4. Gather and analyse data.
  5. Interpret the analysis in relation to the theories introduced at the outset. What have you learned? Do the theories need to be tweaked? For qualitative research, this interpretation and analysis are often interwoven.
  6. Acknowledge limitations of your study. This will likely include reflection about whether your method or the theory are to blame for any mismatch between theory and findings.
  7. Add your findings to the pool of knowledge (after a gauntlet of peer review).
  8. Loop back to 1.

Realist evaluation has similar:

Figure 4.1 and 4.2 from Pawson and Tilley (1997), glued together for ease of comparison. The left loop is taken from a 1970s text on sociological method and the right loop is the authors’ revision for “realist” evaluation.

It is scientific method as usual with constraints on what the various stages should include for a study to be certified genuinely “realist”. For instance, the theories should be framed in terms of contexts, mechanisms, and outcomes (more on which in a moment); hypotheses emphasise the “for whom” and circumstances of an evaluation; and instead of “empirical generalisation” there is a “program specification”.

The method of data collection and analysis can be anything that satisfies this broad research loop (p. 85):

“… we cast ourselves as solid members of the modern, vociferous majority […], for we are whole-heartedly pluralists when it comes to the choice of method. Thus, as we shall attempt to illustrate in the examples to follow, it is quite possible to carry out realistic evaluation using: strategies, quantitative and qualitative; timescales, contemporaneous or historical; viewpoints, cross-sectional or longitudinal; samples, large or small; goals, action-oriented or audit-centred; and so on and so forth. [… T]he choice of method has to be carefully tailored to the exact form of hypotheses developed earlier in the cycle.”

This is reassuringly similar to the standard textbook story. However, like the standard story, in practice there are ethical and financial constraints on method. Indeed the UK government’s evaluation bible, the Magenta Book (HM Treasury, 2020), recommends using Theory-Based approaches like “realist” evaluation when experimental and quasi-experimental approaches are not feasible. (See also, What is Theory-Based Evaluation, really?)

More than a moment’s thought about theory

Pawson and Tilley (1997) emphasise the importance of thinking about why social interventions may lead to change and not only looking at outcomes, which they illustrate with the example of CCTV:

“CCTV certainly does not create a physical barrier making cars impenetrable. A moment’s thought has us realize, therefore, that the cameras must work by instigating a chain of reasoning and reaction. Realist evaluation is all about turning this moment’s thought into a comprehensive theory of the mechanisms through which CCTV may enter the potential criminal’s mind, and the contexts needed if these powers are to be realized.” (p. 78)

They then list a range of potential mechanisms. CCTV might make it more likely that thieves are caught in the act. Or maybe the presence of CCTV make car parks feel safer, which means they are used by more people whose presence and watchful eyes prevent theft. So other people provide the surveillance rather than the camera bolted to the wall.

Nothing new here – social science is awash with theory (Pawson and Tilley cite Durkheim’s 1950s work on suicide as an example). Psychological therapies are some of the most evaluated of social interventions and the field is particularly productive when it comes to theory; see, e.g., Whittle (1999, p. 240) on psychoanalysis, a predecessor of modern therapies:

“Psychoanalysis is full of theory. It has to be, because it is so distrustful of the surface. It could still choose to use the minimum necessary, but it does the opposite. It effervesces with theory…”

Power (2010) argues that most effects in modern therapies can be explained by transference (exploring and using how the relationship between therapist and client mirrors relationships outside therapy), graded exposure to situations which provoke anxiety, and challenging dysfunctional assumptions – for each of which there are detailed theories of change.

However, perhaps evaluations of social programme – therapies included – have concentrated too much on tracking outcomes and neglected getting to grips with potential mechanisms of change, so “realist” evaluation is potentially a helpful intervention. The specific example of CCTV is a joy to read and is a great way to bring the sometimes abstract notion of  social mechanism alive.

The structure of explanations in “realist” evaluation

Context-mechanism-regularity (or outcome) – the organisation of explanation in “realist” evaluations

The context-mechanism-outcome triad is a salient feature of the approach. Rather than define each of these (see the original text), here are four examples from Pawson and Tilley (1997) to illustrate what they are. The middle column (New mechanism) describes the putative mechanism that may be “triggered” by a social programme that has been introduced.

Context New mechanism Outcome
Poor-quality, hard-to-let housing; traditional housing department; lack of tenant involvement in estate management Improved housing and increased involvement in management create increased commitment to the estate, more stability, and opportunities and motivation for social control and collective responsibility Reduced burglary
prevalence
Three tower blocks, occupied mainly by the elderly; traditional housing department; lack of tenant involvement in estate management Concentration of elderly tenants into smaller blocks and natural wastage creates vacancies taken up by young, formerly homeless single people inexperienced in independent living. They become the dominant group. They have little capacity or inclination for informal social control, and are attracted to a hospitable estate subterranean subculture Increased burglary prevalence concentrated amongst the more
vulnerable; high levels of vandalism and incivility
Prisoners with little or no previous education with a growing string of convictions – representing a ‘disadvantaged’ background Modest levels of engagement and success with the program trigger ‘habilitation’ process in which the inmate experiences self-realization and social acceptability (for the first time) Lowest levels of reconviction as compared with statistical norm for such inmates
High numbers of prepayment meters, with a high proportion of burglaries involving cash from meters Removal of cash meters reduces incentive to burgle by decreasing actual or perceived rewards Reduction in percentage of burglaries involving meter breakage; reduced risk of burglary at dwellings where meters are removed; reduced burglary rate overall

This seems a helpful way to organise thinking about the context-mechanism-outcome triad, irrespective of whether the approach is labelled “realist”. Those who are into logframe matricies (logframes) might want to add a column for the “outputs” of a programme.

The authors emphasise that the underlying causal model is “generative” in the sense that causation is seen as

“acting internally as well as externally. Cause describes the transformative potential of phenomena. One happening may well trigger another but only if it is in the right condition in the right circumstances. Unless explanation penetrates to these real underlying levels, it is deemed to be incomplete.” (p. 34)

The “internal” here appears to refer to looking inside the “black box” of a social programme to see how it operates, rather than merely treating it as something that is present in some places and absent in others. Later, there is further elaboration of what “generative” might mean:

“To ‘generate’ is to ‘make up’, to ‘manufacture’, to ‘produce’, to ‘form’, to ‘constitute’. Thus when we explain a regularity generatively, we are not coming up with variables or correlates which associate one with the other; rather we are trying to explain how the association itself comes about. The generative mechanisms thus actually constitute the regularity; they are the regularity. The generative mechanisms thus actually constitute the regularity; they are the regularity.” (p. 67)

We also learn that an action is causal only if its outcome is triggered by a mechanism in a context (p. 58). Okay, but how do we find out if an action’s outcome is triggered in this manner? “Realist” evaluation does not, in my view, provide an adequate analysis of what a causal effect is. Understandable, perhaps, given its pluralist approach to method. So, understandings of causation must come from elsewhere.

Mechanisms can be seen as “entities and activities organized in such a way that they are responsible for the phenomenon” (Illari & Williamson, 2011, p. 120). In “realist” evaluation, entities and their activities in the context would be included in this organisation too – the context supplies the mechanism on which a programme intervenes. So, let’s take one of the example mechanisms from the table above:

“Improved housing and increased involvement in management create increased commitment to the estate, more stability, and opportunities and motivation for social control and collective responsibility.”

To make sense of this, we need a theory of what improved housing looks like, what involvement in management and commitment to the estate, etc., means. To “create commitment” seems like a psychological, motivational process. The entities are the housing, management structures, people living in the estate, etc. To evidence the mechanism, I think it does help to think of variables to operationalise what might be going on and to use comparison groups to avoid mistaking, e.g., regression to the mean or friendlier neighbours for change due to improved housing. And indeed, Pawson and Tilley use quantitative data in one of the “realist” evaluations they discuss (next section). Such operationalisation does not reduce a mechanism to a set of variables; it is merely a way to analyse a mechanism.

Kinds of evidence

Chapter 4 gives a range of examples of the evidence that has been used in early “realist” evaluations. In summary, and confirming the pluralist stance mentioned above, it seems that all methods are relevant to realist evaluation. Two examples:

  1. Interviews with practitioners to try to understand what it is about a programme that might effect change: “These inquiries released a flood of anecdotes, and the tales from the classroom are remarkable not only for their insight but in terms of the explanatory form which is employed. These ‘folk’ theories turn out to be ‘realist’ theories and invariably identify those contexts and mechanisms which are conducive to the outcome of rehabilitation.” (pp. 107-108)
  2. Identifying variables in an information management system to “operationalize these hunches and hypotheses in order to identify, with more precision, those combinations of types of offender and types of course involvement which mark the best chances of rehabilitation. Over 50 variables were created…” (p. 108)

Some researchers have made a case for and carried out what they term realist randomised controlled trials (Bonell et al., 2012; which seems eminently sensible to me). The literature subsequently exploded in response. Here’s an illustrative excerpt of the criticisms (Marchal et al., 2013, p. 125):

“Experimental designs, especially RCTs, consider human desires, motives and behaviour as things that need to be controlled for (Fulop et al., 2001, Pawson, 2006). Furthermore, its analytical techniques, like linear regression, typically attempt to isolate the effect of each variable on the outcome. To do this, linear regression holds all other variables constant “instead of showing how the variables combine to create outcomes” (Fiss, 2007, p. 1182). Such designs “purport to control an infinite number of rival hypotheses without specifying what any of them are” by rendering them implausible through statistics (Campbell, 2009), and do not provide a means to examine causal mechanisms (Mingers, 2000).”

Well. What to make of this. Yes, RCTs control for stuff that’s not measured and maybe even unmeasurable. But you can also measure stuff you know about and see if that moderates or mediates the outcome (see, e.g., Windgassen et al., 2016). You might also use the numbers to select people for qualitative interview to try to learn more about what is going on. The comment on linear regression reveals surprising ignorance of how non-linear transformations of and interactions between predictors can be added to models. It is also trivial to calculate marginal outcome predictions for combinations of predictors together, rather than merely identifying which predictors are likely non-zero when holding others fixed. See Bonell et al. (2016) for a very patient reply.

Conclusions

The plea for evaluators to spend more time developing theory is welcome – especially in policy areas where “key performance indicators” and little else are the norm (see also Carter, 1989, on KPIs as dials versus tin openers opening a can of worms). It is a laudable aim to help “develop the theories of practitioners, participants and policy makers” of why a programme might work (Pawson & Tilley, 1997, p. 214). The separation of context, mechanism, and outcome, also helps structure thinking about social programmes (though there is widespread confusion about what a mechanism is in the “realist” literature; Lemire et al., 2020). But “realist” evaluation is arguably better seen as an exposition of a particular reading of ye olde scientific method applied to evaluation, with a call for pluralist methods. I am unconvinced that it is a novel form of evaluation.

References

Bonell, C., Fletcher, A., Morton, M., Lorenc, T., & Moore, L. (2012). Realist randomised controlled trials: a new approach to evaluating complex public health interventions. Social Science & Medicine, 75(12), 2299–2306.

Bonell, C., Warren, E., Fletcher, A., & Viner, R. (2016). Realist trials and the testing of context-mechanism-outcome configurations: A response to Van Belle et al. Trials, 17(1), 478.

Carter, N. (1989). Performance indicators: “backseat driving” or “hands off” control? Policy & Politics, 17, 131–138.

HM Treasury (2020). Magenta Book.

Illari, P. M., & Williamson, J. (2011). What is a mechanism? Thinking about mechanisms across the sciencesEuropean Journal for Philosophy of Science2(1), 119–135.

Lemire, S., Kwako, A., Nielsen, S. B., Christie, C. A., Donaldson, S. I., & Leeuw, F. L. (2020). What Is This Thing Called a Mechanism? Findings From a Review of Realist Evaluations. New Directions for Evaluation, 167, 73–86.

Marchal, B., Westhorp, G., Wong, G., Van Belle, S., Greenhalgh, T., Kegels, G., & Pawson, R. (2013). Realist RCTs of complex interventions – an oxymoron. Social Science & Medicine, 94, 124–128.

Pawson, R., & Tilley, N. (1997). Realistic Evaluation. SAGE Publications Ltd.

Pawson, R., & Tilley, N. (2004). Realist evaluation. Unpublished.

Power, M. (2010). Emotion-focused cognitive therapy. London: Wiley.

Whittle, P. (1999). Experimental Psychology and Psychoanalysis: What We Can Learn from a Century of Misunderstanding. Neuropsychoanalysis1, 233-245.

Windgassen, S., Goldsmith, K., Moss-Morris, R., & Chalder, T. (2016). Establishing how psychological therapies work: the importance of mediation analysis. Journal of Mental Health, 25, 93–99.