I have woven together these two threads as they both cover the topic of what a mechanism is and also touch on the issue of focussing reviews.

- Mechanisms. What is a mechanism is probably one of the most ‘asked’ questions in realist research. Gill’s answer is as good as anyone’s and certainly allows this concept to be usable - 'resources + reasoning = mechanism'. In addition Gill outlines that a mechanism has at least three elements:
“… the resource or opportunity the program provides, the changed reasoning on the part of the target, and the process by which the changed reasoning leads to changed behaviours which generate different outcomes.”

- CMOs or should we say OMCs? The issue of what (in realist concepts) any one ‘factor’ is arose. The point made was that depending on where within a programme theory one might be, a ‘factor’ might be a Context (C), Mechanism (M) or even an Outcome (O). The trick worth re-emphasising here is in any realist analysis to first start with the O – the outcome of interest. This may be an ‘intermediate’ outcome within a programme theory or the main outcome of interest. But by starting at the O, it might be easier to identify the Cs and Ms that are relevant to it.
Such an analytic strategy might also help to make a review more manageable as Cs and Ms not relevant to an O of interest could be justifiably put to one side.

- A very pragmatic and necessary suggestion came from Colleen which was that in order to make a review manageable, it was important to spend time focussing down the review. The reality is that a realist review could go on forever and having a sensible way for reducing its breadth and depth is important. Suggestions made included (for example) focusing on important outcomes, outcomes of interest to your audience, policy relevant outcomes and so on.

- Finally if you are looking for suggestions on books that might help to make realism more accessible, suggestions included:
Health and Social Change: A Critical Theory by Graham Scrambler, Open University Press, 2002.
Realism and Social Science by Andrew Sayer, Sage, 2000

Geoff