I am reading a paper by Rycroft-Malone and colleagues (2004) about what constitutes evidence in evidence-based nursing practice. This paper is interesting because it emphasises a plurality of evidence. The authors identify four sources of evidence—from research and scholarship, professional knowledge and clinical experience, local data and information, and patient experiences and preferences—while at the same time they consider this evidence, from whatever source, to be strongly constructed. My comments consider a realist response to this notion of construction of evidence, and the implications of knowing that researchers always bring prejudices, prejudgements, frames of reference, and concepts to their choice of cases.
The first point to say about realist methodology is that it is accepting of the idea of a broader definition of what constitutes evidence. On this point we can agree with Rycroft-Malone and colleagues. Further, the ways in which these authors move away from propositional evidence, which has traditionally informed practice, and point to the importance of professional tacit knowledge and experience and how this is crafted into understandings of particular issues, how patient experience must be part of the account, and the key role of context in any evidence collection are all issues we would strongly agree with.
However, we depart from Rycroft-Malone and colleagues’ conceptualisation of evidence. First, realists can not accept the claim that evidence is strongly constructed. These authors claim that both propositional and non-propositional evidence is constructed. Certainly it is the case that any evidence is constructed, we would argue. The issue is whether that construction is strong or weak. Strong constructions are particular, emergent, and discovered from empirical evidence. If the evidence is strongly constructed then it describes what works for whom in what context. Evidence conceived of as strongly constructed provides opportunities for an endless stream of narrative accounts, bespoke stories to fit every patient, or health care professional, or scientist’s construction in particular contexts.
If, however, the construction in the evidence is weak, as realists argue, then the realist question, what works for whom in what circumstances, and WHY can be answered.
To take an example Rycroft-Malone and colleagues use, they discuss uptake of low molecular weight heparin as antithrombolytic prophylaxis for elective joint replacement. According to Ferlie, whose study Rycroft-Malone and colleagues’ draw on, the use of heparin ‘was influenced by the beliefs of a core group of orthopaedic surgeons, whose views were based on experiential knowledge’ (pg. 85). This can be read in two ways. For Rycroft-Malone colleagues this is a strong construction: this insight shows how this particular group of orthopaedic surgeons view heparin, another group will think differently.
For realists, this points to a weak construction, some orthopaedic surgeons think this is an appropriate treatment and there must be a reason or reasons why they think like this, when much of the empirical evidence is equivocal. It is these underlying (often invisible or indirectly observable) causes that spur these consultants to make choices about whether to use heparin or not that realism is interested to investigate.
The second and interrelated difference hinges on what empirical evidence provides by way of insight. What we can say about Rycroft-Malone and colleagues’ account of evidence is that it is ontologically flat, by which I mean that what is considered to be evidence consists only of what can be measured, observed, said, or recorded in some way, even when from a rich variety of sources. Whereas realists, similarly catholic about evidence, add another dimension to their account of evidence, they are interested in evidence that has a stratified and deep ontology. The surface appearance of things may well provide a rich description of what is going on, but it does not explain the powers, liabilities, and dispositions that lie beneath the surface of things (often quite deeply)that explain the real.
In short, Rycroft-Malone colleagues’ account of evidence is entirely horizontal. It is made up of strongly constructed accounts from science, practitioners, surveys of context, and patients. Realists add vertical stratification and depth to this account of evidence, they search for indirect, invisible, or even hypothesised evidence to get at the causes that lie beneath empirical observation.
Why does this matter? Well the reason why I am reading this paper is because we are designing a study with the provisional question ‘Is there a difference between the repositioning behaviours of patients and staff when using an alternating pressure mattress (APM) or high specification foam (HSF) mattress.’? This is a very important question to ask because the UK National Health Service spends a great deal of money (it is said between 4-5% of its budget) dealing with pressure sores. Leaving aside these costs, no one should have to endure these preventable wounds. In designing the study, we could draw on the kinds of flat empirical evidence, from research and scholarship, professional knowledge and clinical experience, local data and information, and patient experiences and preferences as outlined by Rycroft-Malone and colleagues. The outcome will be a descriptive answer ‘yes’ or ‘no’, or something in between. But we will not be able to explain why there is (or is not) a difference. To do this we need ideas about some of the assumptions that underlie and are implied in the overarching question articulated here. So, for instance, it might be that ward policy has a particular impact on the way in which patients are moved, nurses might approach the care of patients in different kinds of beds differently, or patients might find it harder to move around in one kind of bed and easier to care for themselves in another. Our investigation starts with ideas like these and uses methods (always in the service of ideas) to test these out. Our intention is to move beyond being able to describe instances towards outing the causal processes that explain observed differences.
The same challenges arise for sampling in research. The ideas about why something is happening are always the starting point in making choices about who or what to include in the research. Researchers always bring prejudices, prejudgements, frames of reference, and concepts to their choice of cases.