Friday I talked about how "Top down vs. Bottom up" structure would affect your choice between message boards and social network systems. Today I'm going to talk about how churn may affect your decision.

Low vs. high churn rate
Another question to ask yourself is what the churn rate on the site will be like. Do most participants post a few times? Or do most participants post regularly?

Message boards can support sites with both a low or high churn rate, but we strongly recommend them on sites such as support sites where most users only log in once in a while to ask a question. Message boards are ideally suited to these kinds of uses, since users can quickly create an account and post their questions. Social networks, with their more elaborate profiles, present a bigger hurdle to users who just want to ask a question and don't necessarily want to get involved in a community.

On the other hand, if you have a site where you have a core of stable participants, social networks provide additional benefits for long-term members. As an in-house example, our company used to use our message board product for our intranet. We used it when we had to discuss issues that spanned across departments, but it was fairly quiet. When we shifted to a social network, our intranet blossomed. In addition to starting discussions, people began contributing interesting finds to their blogs and posting photos.

So, which product is best for you?
It depends on what you're trying to achieve. If you have a top-down community, or a community with a high churn rate, I'd recommend a message board community. If you have a bottom-up community, or a community with a stable core of users, I'd recommend a social network.

Read part 1