Table 1.

Overall assessment of methodological quality within a primary study and across all primary studies following Higgins et al. (2011).

Methodical quality	Within trial	Across trials
Weak Methodical quality (3)	Two or more weak (3) component ratings	More than 50 % of the studies have a weak (3) global rating
Moderate Methodical quality (2)	One weak (3) component rating	More than 50 % of the studies have a moderate (2) global rating
Strong Methodical quality (3)	No weak (3) component rating	More than 50 % of the studies have a strong (1) global rating