PT  - JOURNAL ARTICLE
AU  - Craig, Peter
AU  - Cooper, Cyrus
AU  - Gunnell, David
AU  - Haw, Sally
AU  - Lawson, Kenny
AU  - Macintyre, Sally
AU  - Ogilvie, David
AU  - Petticrew, Mark
AU  - Reeves, Barney
AU  - Sutton, Matt
AU  - Thompson, Simon
TI  - Using natural experiments to evaluate population health interventions: new Medical Research Council guidance
AID  - 10.1136/jech-2011-200375
DP  - 2012 Dec 01
TA  - Journal of Epidemiology and Community Health
PG  - 1182--1186
VI  - 66
IP  - 12
4099  - http://jech.bmj.com/content/66/12/1182.short
4100  - http://jech.bmj.com/content/66/12/1182.full
SO  - J Epidemiol Community Health2012 Dec 01; 66
AB  - Natural experimental studies are often recommended as a way of understanding the health impact of policies and other large scale interventions. Although they have certain advantages over planned experiments, and may be the only option when it is impossible to manipulate exposure to the intervention, natural experimental studies are more susceptible to bias. This paper introduces new guidance from the Medical Research Council to help researchers and users, funders and publishers of research evidence make the best use of natural experimental approaches to evaluating population health interventions. The guidance emphasises that natural experiments can provide convincing evidence of impact even when effects are small or take time to appear. However, a good understanding is needed of the process determining exposure to the intervention, and careful choice and combination of methods, testing of assumptions and transparent reporting is vital. More could be learnt from natural experiments in future as experience of promising but lesser used methods accumulates.