Regarding user retention… it seems that on almost every StackExchange site, only one quarter of the users ever post more than once or twice. Does Code Review fit that pattern? If so, does user retention matter much?
Here's my methodology:
- For all users of a site who have asked or answered anything, count their questions and answers.
- For each user, the number of questions + answers is their "activity".
- Categorize users according to their quintile of activity.
- For each quintile of users, get the average reputation, the average proportion of posts that are questions, and the average proportion of posts that are answers.
Compare the results:
- Code Review: 4th quintile has 1.8 posts per user, 5th quintile has 9.1 posts per user.
- Web Applications: 4th quintile has 1.4 posts per user, 5th quintile has 9.2 posts per user.
- Programmers: 4th quintile has 2.4 posts per user, 5th quintile has 21.0 posts per user.
- Server Fault: 4th quintile has 2.5 posts per user, 5th quintile has 22.5 posts per user.
- SuperUser: 4th quintile has 2.0 posts per user, 5th quintile has 17.2 posts per user.
- Ask Ubuntu: 4th quintile has 1.4 posts per user, 5th quintile has 11.0 posts per user.
- English: 4th quintile has 1.9 posts per user, 5th quintile has 22.7 posts per user.
The pattern is consistent: nearly all the activity comes from the top quartile of users, and the bulk of the users are drive-bys. There are some minor differences — for example, the top quintile of Programmers users skew towards answering, and the the bottom half of Ask Ubuntu users skew towards asking.
I'd like to point out that the statistics for Code Review are very similar to Web Applications, a graduated site, in other ways as well: