Jing Jing: biases in medical testing are not just gender based but also race based. Most pop-psychology “universals” are based on American college students from select universities. The “selection” bias with human subjects is interesting — of course the dominant populace (males, whites …) is over-represented, but one subtle effect is that minority researchers have difficulty attracting enough of the dominant population for their studies, and then their work is criticized for not being “representative enough”.