Methodologically, the national evaluation comprised
a realistic evaluation design (Pawson and
Tilley, 1997) within which a ‘theories of change’
approach was embedded. The realistic evaluation
design was chosen because more traditional evaluation
designs cannot capture the outcomes of health
promotion initiatives that are likely to be long-term
and influenced by a range of external variables for
which it is not possible, or necessarily desirable, to
control. In addition, although traditional evaluation
designs can shed light on what is or is not effective,
they are unable to answer the crucial questions of
why something works, for whom and in what circumstances.
In contrast, realistic evaluation places
emphasis on the mechanisms through which initiatives
achieve particular outcomes in certain contexts,
described by Pawson and Tilley as ‘context,
mechanism and outcome configurations’. The way
in which we interpreted and applied these terms is
summarized in Table II.and attributing outcomes). The theories of change
approach thus fits well with the realistic evaluation
design, facilitating a more in depth exploration of
the relationships between contexts, mechanisms and
outcomes