Table 1.

Components of the 132 systematic reviews that included a meta-analysis.

	Mean (SD)	Median	Range	Comments
Trials in the meta analysis	7.3 (11.6)	4.0	2 to 184	Does not include the 35 reviews with a single trial
Weight of the most precise trial	50% (22.0)+-	51%	3.3 to 96.4	Weight is based on the inverse variance calculated in RevMan
Sample size in most precise trial	1148 (7392)	183	14 to 82,892
P value for meta analysis	0.21 (0.29)	0.03	0.0 to 0.99
Degree of Heterogeneity - I2	26.6% (30%)	1.2%	0% to 90%	Does not include the 35 reviews with a single trial