[Pilfer]

The effect size is quite large. From the paper,

The differences were substantial: in some cases, such as total brain volume, more than a standard deviation. The effect size of d = −1.41 for total brain volume (Table 1) translates to 92.1% of males being above the female mean, and an 84.1% chance that a randomly-chosen male will have a larger total brain volume than a randomly-chosen female.