I've got 8.98:1 (practically 9:1) ratio. My threads are not usually huge hits, and some of them are complete misses, but I don't bother. It keeps me humble to see how little interest I generate. On the other hand, there's usually a fair amount of replies, and I think the topics get handled just OK. I don't usually invite much side-tracking, but I really enjoy the responses people make. Usually my motive is not to encourage social interaction, even though I enjoy it real life, but to discuss a topic. I feel that many obscure and esoteric topics get handled here MUCH better than in real life conversations, face to face.
I think I was on top10 list of thread starters a while ago. So, my main points in starting threads are curiosity and brainstorming, bouncing off ideas, and examining a topic. I have zero interest in winning anyone in an internet discussion, but I often use a debating method of examining some topic, to see how the idea survives the debate. For me, an honorable debate, for pro and against some idea, is a good method for examining how some piece of fact or some idea can survive.
Then again, I think there's too much a "harmonious" mood in many of my threads. Sometimes I ridicule people's opinions, but at a much lower rate than I see in general discussions. I think that threads where people offend each other go on for longer and invite more spectators. I don't do any of that so often, and I don't often have extreme views, so I'm more of a boring babbler who goes on and on and takes a middle-of-the-road approach to many subjects. See this post right here?