RT Journal Article SR Electronic T1 What’s casual? What’s causal? Advancing research on employment relationships and health JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 1 OP 3 DO 10.1136/oemed-2020-107136 VO 78 IS 1 A1 Trevor Peckham A1 Noah S Seixas YR 2021 UL http://oem.bmj.com/content/78/1/1.abstract AB