Maybe it's because you're using a contrived example, but I don't quite agree. These sort of studies are usually undertaken at a higher, more abstract level. eg. How do various cognitive abilities differ between sexes? With the resulting data, we might be able to explain certain phenomena, or dispel certain stereotypes. But I don't think we're anywhere close to being in a position we can say x out y men/women would make excellent engineers. That kind of information is usually extracted from trend analyses (eg. studying the proportion of males/female engineers who are highly successful at their career vs those who aren't), and they're inherently skewed because of the nature of the society we live in.