RT Journal Article SR Electronic T1 Use of the prevalence ratio v the prevalence odds ratio as a measure of risk in cross sectional studies. JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 841 OP 841 DO 10.1136/oem.51.12.841 VO 51 IS 12 A1 J Lee A1 K S Chia YR 1994 UL http://oem.bmj.com/content/51/12/841.1.abstract AB