RT Journal Article SR Electronic T1 RESEARCH FOR PRACTICAL PUBLIC HEALTH JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 641 OP 641 DO 10.1136/jech.56.9.641 VO 56 IS 9 A1 John R Ashton A1 Carlos Alvarez-Dardet YR 2002 UL http://jech.bmj.com/content/56/9/641.abstract AB