The Greater Male Variability Hypothesis (GMVH) suggests that males exhibit greater variance than females in their cognitive abilities. I present some relevant empirical findings and make a suggestion for how the hypothesis should be conceptualized and evaluated.

I think you should not use the variance ratio, as this metric is not interpretable by intuition. I think people use it because there is a known statistical test for it. The ratio of the standard deviations is better for understanding. So in your results, VR's are 1.16, 1.22, 1.23, mean is 1.20. Sqrt of 1.20 is 1.10, i.e. 10% greater for males. So in terms of IQ, this would correspond to SD's of about 15.7 to 14.3.

But taking VR0 is an egalitarian fault. We know males have higher intelligence by 4-5 points in adulthood, d=0.2 to 0.4 so true VR is not VR0 but about VR0.3 so clearly higher than 1,2...

Could this be the result of decreased variation in X-linked gene effects due to female X-inactivation?

Male X-linked genes are always producing a single set of genetics products, but female X-linked genes experience an averaging process in tissues expressing X-linked genes (i.e. practically all of them) that plausibly reduces variation in the X-linked effect sizes.

## Understanding Greater Male Variability

I think you should not use the variance ratio, as this metric is not interpretable by intuition. I think people use it because there is a known statistical test for it. The ratio of the standard deviations is better for understanding. So in your results, VR's are 1.16, 1.22, 1.23, mean is 1.20. Sqrt of 1.20 is 1.10, i.e. 10% greater for males. So in terms of IQ, this would correspond to SD's of about 15.7 to 14.3.

But taking VR0 is an egalitarian fault. We know males have higher intelligence by 4-5 points in adulthood, d=0.2 to 0.4 so true VR is not VR0 but about VR0.3 so clearly higher than 1,2...

Could this be the result of decreased variation in X-linked gene effects due to female X-inactivation?

Male X-linked genes are always producing a single set of genetics products, but female X-linked genes experience an averaging process in tissues expressing X-linked genes (i.e. practically all of them) that plausibly reduces variation in the X-linked effect sizes.

Thanks. I like to see means and standard deviations, and also a plot of the shapes of the distributions, in case they give us some insights.