Over the years my coder colleagues have been about 95% male and 5% female. Of them, I rate about 80% of the males as producers of quality code, and about 95% of the females as such. That's just my experience and my subjective scores.
- 380 men
- 19 women producing good code
- 1 woman producing bad code
I think the error bars on that one woman would be quite large, too large to draw any conclusions.
Now if I guessed wrong and you've actually had not 400, but tens of thousands of colleagues who you've been secretly tracking and ranking in your spare time, maybe you'd have enough data to draw a conclusion.
I'll be just as lazy...4x the number of male duds across that number of observations? It's going to be statistically significant.
In any case, I would generally agree with your take but express it a bit differently— the group of programmers who really blow me away with their ingenuity and commitment to excellence has significantly more women in it than the larger population ratio suggests should be expected.