I wonder if even a small imbalance could almost completely explain it.

If a gender is less likely to be able to find a Significant Other (we'll assume that homosexuality exists in equal proportions in both genders), would they be more likely to take risks than the other gender? It wouldn't take much of a difference to make a large change in founder figures, since such a small amount of people try to start a company.

New York City is one of the most culturally diverse cities in the world, and I'll bet that the diversity in New York is evident in New York's tech scene.

Many cities like to claim this, but NY barely makes the top 10. For example, Dubai has way over 75% foreign residents. And cities like Toronto and Sydney are both statistically and anecdotally more culturally diverse.

I'd be more interested in the number of fashion/wedding startups in NY and the percentage of females who run said startups. Huge stereotype and completely unfounded, but it wouldn't surprise me either.

New York's natural born citizens are culturally diverse.

Exactly. I remember reading dating scene analyses that report the ratio of 2:1 for men and women around SF whereas in NYC it is just the reverse. This neatly explains the x2 factor.

A female population of 52.5% explains the effect for dating, but not for founding companies. The difference is because it's the surplus that matters for dating but the entire population for founding.

Suppose that 42.5% of the population are women in a marriage or committed relationship, and then by definition 42.5% are also committed men. That leaves 10% of the population as single females and 5% as single males, and there's your 2:1 ratio for dating, created by just the small female surplus.

Would that hold for founding companies? I don't think so. Any of the 52.5% females could start a business, as could any of the 47.5% males. The small excess of women doesn't create a 2:1 ratio here. (There may be some correlation, that married and settled women are less likely to start a business, but the population ratio can't explain the entire outcome.)

I don't know if the startup founder demographic is well defined enough to make a definitive statement.

There are probably significant demographic divisions (race, educational background, housing rent/own ratio, size of industry clusters, national origin, income distribution, etc) that probably have an impact.

The data above doesn't support that - there's only about a 2% difference.

Gender imbalances are more dramatic in the 20-60 population than 0-20 because children have less say in where they live. In other words a 32 year old male might decide to move based on a gender, but people rarely move based on the gender of their children.

Also, a high percentage of dating age people are in a relationship. If there is a 48:52 gender imbalance in 25-45 year old population. And 2/3 the women are in a relationship (ignoring the same sex relationships) the gender imbalance is more significant among the single population. 48 /3 vs 52 - (48*(2/3)) is 16:20 or 44.4:55.6

Here's the proof, all the single ladies, all the single ladies, are on the East Coast: http://www.boston.com/bostonglobe/ideas/articles/2008/03/30/...