Smoking cessation programmes, typically aim to positively change a health behaviour, which in turn, is determined by a diverse range of individual (e.g. cognitive and affective) and environmental (social and cultural) factors. Moreover, such interventions set out to achieve positive outcomes in ever changing social, organisational, economic and political contexts [21
These types of interventions are not easily evaluated by traditional experimental designs [24
]. Health researchers are increasingly urged to use evaluation designs which not only capture outcomes but which also elucidates implementation processes, and contextual factors (internal and external) that may influence the success (or otherwise) of an intervention. Collectively, these data can provide a clearer link (or otherwise) between the intervention and observed outcomes; thus making any claims of attribution more valid [28
]. Furthermore, it is important to ensure 'implementation failure' is eliminated as an explanation for the failure of some programmes to reach their desired outcomes [32
It is also crucial to identify relevant process and outcome indicators that accurately reflect the nature and intensity of the intervention under review [32
]. Ideally, the process of identifying relevant indicators and measures should be done as a participatory and collaborative process with all key stakeholders [36
Phased study designs are posited as an evaluation approach that can: (a) map the context, components and complexity of emergent health promotion interventions; and (b) identify and select plausible and realistic process and outcome measures on which to judge the merit or worth of the intervention at a later point in time. The MRC (Medical Research Council) framework for example, recommends - as a first stage - that the 'active ingredients' of an intervention, and its likely impact on health outcomes are identified, before attempting a larger scale intervention study [28
The Theory of Change (ToC) approach, which has been championed by realist methodologists, [4
] was developed in the US in an effort to find ways of evaluating processes and outcomes in community-based programmes that were not adequately addressed by existing approaches [37
]. The ToC approach is defined as 'a systematic and cumulative study of the links between activities, outcomes and contexts of the initiative'
]. In generating a programme ToC, steps are taken to link the original problem; the context in which the programmes operates; the planned activities with its intended medium and longer-term outcomes.
Previous research suggests that evaluators should engage with key stakeholders at the early planning and development stage to identify a programme ToC that will link outcomes and activities and explain how
the desired change is expected to come about [21
]. Proponents of ToC often advocate the use of logic models in this process, as a means of identifying an intervention's inputs and activities and its intended outcomes [39
Aims and objectives
The overall aim of this study is to evaluate six SCPPs offering smoking cessation support services; three are aimed at young people and three at pregnant women living in Grampian. As this protocol is based on realist evaluation [4
], there is no hypothesis, but the two overarching research questions were: "How did the interventions operate?" and "Did they reach their own aims and objectives?"
The objectives of the evaluation are to establish:
1. the intervention processes;
2. any changes made to the six interventions in response to local conditions;
3. the uptake of the services by the intended target group;
4. the degree to which project services become established and stable;
5. the acceptability of the interventions by intended clients and service providers;
6. to what extent the SCPPs met their short and medium term-objectives;
7. the feasibility of further roll out of promising interventions to other areas.
Given the ambiguity of the proposed interventions, the research team proposed a ToC approach to develop an evaluation framework.