A fundamental step in the implementation of an intervention is anticipating, planning and carrying out its evaluation. This ensures proper use of the often limited resources and available means (including financial means). The evaluation also provides a basis for optimising future interventions and improving their impact.
The evaluation can involve various disciplines: public health, epidemiology, clinical research, statistics, social psychology, sociology, economics, etc.
There are many methods for performing an evaluation and, regardless of the means allocated and the evaluators’ competences; there will always be a way to optimise an intervention through evaluation.
The evaluation is constructed by a group of local partners and evaluation professionals at the time of definition of the intervention itself and its protocol. At this stage, it is advisable to determine the indicators to be tracked, which depend on the objectives of the intervention. When making a request for funding – which is usually before the intervention is implemented – the cost of the evaluation should be integrated where possible.
The different types of evaluation
- Process evaluations. These evaluations are usually the simplest to deploy and they can provide very useful information. They describe the intervention actually implemented, which may differ from that initially envisaged, and measure the immediate impact on the intermediate objectives (implantation, notoriety of a campaign, etc.), which are not the final objectives of the intervention (behavioural change).
- Evaluating effectiveness, outcome or impact. These evaluations are more complex to design, implement and analyse. They must answer the question of whether the intervention has achieved its specific objective(s). As such, in addition to the question of ‘was the campaign seen?’ (process evaluation), the following is asked: ‘did exposure to the campaign affect the target’s knowledge or behaviour?’ (according to the defined objectives).
Using a logic model to help design the evaluation
When preparing an intervention, setting out a logic model helps to improve the intervention and to design the evaluation protocol. In this way, a logic model is a tool that facilitates the planning, implementation and evaluation of interventions.
A logic model is a schematic representation of the desired intervention, its objectives and the supposed deployment mechanisms. This tool should explain the logic of the intervention (its target determinants) and how we think that it will achieve its objectives. It can have different degrees of complexity.
Example:
Resources - guides for implementing evaluations
- Evaluation d'une action de santé publique : recommandations
French National Authority for Health (HAS), 1995 - Framework for Program Evaluation in Public Health
Centers for Disease Control and Prevention (CDC), 1999 - Introduction to Program Evaluation for Comprehensive Tobacco Control Programs
Centers for Disease Control and Prevention (CDC), 2001 - Introduction to Program Evaluation for Public Health Programs: a Self-Study Guide
Centerws for Disease Control and Prevention (CDC), 2011 - Evaluation Handbook
W.K.Kellogg Foundation, 2004 - Logic Model Development Guide
W.K.Kellogg Foundation, 2004
The Centers for Disease Control and Prevention (CDC) have many tools and guides to help with implementing evaluations in public health. All their resources are available on their website.