Why are women stereotyped as more talkative than men?

There is no hard evidence as to which gender speaks more. It's an incredibly vague question and anyone who tries to give a definite answer doesn't have all the facts.

It seems that who speaks more depends on the motives and subject matter. As loose model, women might go on for hours speaking about family and friends, but guys can often go on for hours about sports teams, technical things, and themselves. However, it really varies per person and per conversation.