Assessing the evaluability of complex public health interventions: Five questions for researchers, funders and policymakers

Abstract

Government policies and programmes to improve public health can often be regarded as complex interventions, in that they typically involve the flexible or tailored implementation of multiple interacting activities in a variety of settings to bring about population behaviour change and health improvement. However, evidence to support their development and implementation is often weak. Recognition of this ‘knowledge gap’ has led to repeated calls for more and better evaluation of the health impact of these complex ‘natural experiments’. Few may disagree in principle with the evaluative ‘call to arms’, but its implementation raises a number of scientific, practical and prioritisation issues, especially in a climate of public sector financial restraint.