RT Journal Article SR Electronic T1 Healthy worker effects explain differences in internal and external comparisons in a rubber industry cohort study JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 781 OP 781 DO 10.1136/oemed-2019-106083 VO 76 IS 10 A1 Mira Hidajat A1 Damien Martin McElvenny A1 Peter Ritchie A1 Andrew Darnton A1 William Mueller A1 Martie van Tongeren A1 Raymond M Agius A1 John W Cherrie A1 Frank de Vocht YR 2019 UL http://oem.bmj.com/content/76/10/781.abstract AB