# Table 3 Statistical comparison of the profiles of limitations between studies with positive and negative results

Risk of bias Imprecision
Total number of key questions judged to be at high risk of bias Number of key questions judged to be at high risk of bias in favour of a null result Number of key questions judged to be at high risk of bias with uncertain direction on study outcome Studies with key question judged to be at high risk of bias in favour of an effect of exposure Studies judged to have concern regarding statistical power Studies judged to have concern regarding missing adjustment for multiple comparisons when relevant
Median (Interquartile range) Median (Interquartile range) Median (Interquartile range) n (%) n (%) n (%)
Studies with positive results 3.0 (4.0) 2.0 (4.0) 1.0 (2.0) 2 (29%) 6 (86%) 2 (29%)
Studies with negative results 2.0 (2.0) 2.0 (1.5) 0 (1.5) 5 (26%) 15 (71%) 10 (48%)
Test statistics and p-values Mann-Whitney-U:
U = 55.5
p = 0.351,4
Mann-Whitney-U: U = 65.0
p = 0.682,4
Mann-Whitney-U: U = 54.5
p = 0.322,4
Fisher’s exact: p = 1.002 Fisher’s exact: p = 0.643 Fisher’s exact: p = 0.663
1. Significance levels: 1α = 0.05, 2α = 0.017, 3α = 0.025
2. 4Exact significance