Table 6. Study assessments—quantitative studies.

Authors (year)	Did study address a clearly focused issue?	Cohort/ sample recruited in an acceptable way?	Exposure accurately measured to minimise bias?	Outcome accurately measured to minimise bias?	Have authors identified important confounding factors?	Have authors accounted for confounding factors in design and/or analysis?	Was follow up of participants long enough?	Do you believe the results?	Can results be more widely applied?	Overall quality rating
Anshel, Umscheid & Brinthaupt (2013)	Yes	Yes	Can’t tell	Yes	No	No	Can’t tell	Can’t tell	Can’t tell	Weak
Doerner (1987)	Yes	Yes	N/A	No	N/A	N/A	N/A	No	No	Weak
James & Wright (1991)	Yes	Yes	N/A	Can’t tell	N/A	N/A	N/A	Can’t tell	Can’t tell	Weak
Jenkins (1997)	Yes	Can’t tell	N/A	Yes	N/A	N/A	N/A	Yes	Can’t tell	Moderate
Pierce & Lilly (2012)	Yes	Yes	N/A	Yes	N/A	N/A	N/A	Yes	Yes	Strong
Shakespeare-Finch, Rees & Armstrong (2014)	Yes	Yes	N/A	Yes	N/A	N/A	N/A	Can’t tell	Can’t tell	Moderate
Sprigg, Armitage & Hollis (2007)	Yes	Can’t tell	N/A	Can’t tell	N/A	N/A	N/A	Yes	Can’t tell	Weak
Wastell & Newman (1996)	Yes	Yes	Yes	Yes	Can’t tell	Can’t tell	Can’t tell	Yes	Yes	Moderate
Weibel et al. (2003)	Yes	Can’t tell	Can’t tell	Yes	Yes	No	No	No	Can’t tell	Weak