Table 2. Risk of bias.

Risk of bias assessment related to included studies (modified from Lopes et al., 2012).

Included studies	Criteria
	1	2	3	4	5	6	7	8	9	10	Total
Bradbury & Forman (2012)	0	1	1	1	1	0	0	0	0	0	4
Chou et al. (2015)	1	1	1	1	1	0	0	0	0	0	5
Crotin et al. (2013)	1	1	1	U	1	0	0	0	0	0	4
Crotin et al. (2014)	0	1	1	1	1	0	0	0	0	0	4
Dale et al. (2007)	0	1	1	0	1	0	0	0	0	0	3
Erickson et al. (2016)	1	1	1	1	1	0	0	0	0	0	5
Escamilla et al. (2007)	1	1	1	0	1	0	0	0	0	0	4
Freeston et al. (2014)	0	1	1	U	1	0	0	0	0	0	3
Grantham et al. (2014)	0	1	0	1	1	0	0	0	0	0	3
Keeley, Barber & Oliver (2010)	0	1	1	1	1	0	0	0	0	0	4
Keeley et al. (2017)	0	1	1	1	1	0	0	0	0	0	4
Lyman et al. (2001)	0	1	1	U	1	1	1	0	0	1	6
Lyman et al. (2002)	1	1	1	U	0	1	1	0	0	1	6
Makhni et al. (2014)	1	1	1	U	1	1	1	0	0	1	7
Mullaney et al. (2005)	0	1	1	0	1	0	0	0	0	0	3
Murray et al. (2001)	0	1	1	1	0	0	0	0	0	0	3
Oliver & Plummer (2010)	0	1	1	0	1	0	0	0	0	0	3
Oliver, Weimar & Henning (2016)	0	1	1	U	1	0	0	0	0	0	3
Sonne & Keir (2016)	1	1	1	0	1	0	0	0	0	0	4
Tripp, Yochem & Uhl (2007)	0	1	1	0	1	0	0	0	0	0	3
Wang et al. (2016)	1	1	0	U	1	0	0	0	0	0	3
Warren, Szymanski & Landers (2015)	0	1	1	U	1	0	0	0	0	0	3
Whiteside et al. (2016)	1	1	1	1	1	0	0	0	0	0	5
Yang et al. (2014)	1	1	1	1	1	1	1	1	0	1	9
Yang et al. (2016)	0	1	1	1	1	0	0	0	0	0	4

Note:

Scoring: “low risk of bias” = 1, “high risk of bias” = 0, “unable to determine” = U (scored as 0)