You're right. What's important isn't how many people tweet, it's how many people sign up. Of course 20% of new signups will tweet, they get a free month for it.

You're right. What's important isn't how many people tweet, it's how many people sign up. Of course 20% of new signups will tweet, they get a free month for it. That's why you give a user-specific shortened link with UTM values for people to tweet out and don't simply reward them for tweeting your site name or address.