It's reasonable to think that the bias would decrease over the company's lifetime. In early rounds there is little data on the company, so more decisions are m

It's reasonable to think that the bias would decrease over the company's lifetime. In early rounds there is little data on the company, so more decisions are made on hunches, and there's a lot of potential influence for bias. While there's potential for that in later rounds too, there's also a lot more objective information. The company is either making money or it isn't. The importance of relationships to the funding round also plays a role. If you get as far as an IPO, it seems unlikely that the stock-buying public is going to stay away because the founders are female/black/etc.