Abstract
This research was carried out to ascertain the different types and sources of evidence commonly applied to the Health Impact Assessment (HIA) process in the United Kingdom; and to also examine the factors that influence the derivation and usage of the different types of evidence. A questionnaire survey of 52 HIA practitioners who had conducted a total of 103 HIAs over a 3βyear period was carried out, followed by semiβstructured interviews of 11 practitioners to gain deeper insights into the questionnaire findings. Ten different sources of evidence were seen to have been applied to the HIA process. Literature review was discovered to be the most commonly utilized source of evidence, having been used by 37 out of 52 practitioners (71.2%) and in 83.5% of the 103 HIAs. Engagement with local residents was second in terms of usage by practitioners (69.2%) and expert opinion was third, having been used by 67.3% of respondents. Other sources of evidence included completed HIA reports, survey, modelling and Delphi exercises. The findings point to efforts to ensure that predictions are grounded on robust sources of evidence, although several issues need to be addressed in the pursuit of evidenceβbased HIA (EBHIA). Copyright Β© 2010 John Wiley & Sons, Ltd.