Table 3.

Linear regression model fitted on log impact factor

Explanatory variables*	B coefficient(95% CI)
Country income	0.490(0.249 to 0.730)
Publication year	0.269(0.060 to 0.479)
Log Study sample size†	0.197(0.103 to 0.291)
Language of publication	0.976(0.247 to 1.70)
Randomization	Not selected
Blinding	Not selected
Statistical significance	Not selected

*The randomization, use of blinding and statistical significance were not selected in the final forward stepwise regression model.

^†Logarithmic transformation because of a large right skewness.