Hamids54, how are you defining "active?" Are you using a metric like recency of visiting the site? Posting? There's little doubt that a better community has a higher ratio of active to inactive, but this will change over time. I.e., a five year old forum will likely have more members who have stopped posting than a one year old forum, even though it may be a vibrant community.
yes time of registering of the forums should not be far look at my comparing.the forum that I first mentioned the second forum is older than me but its posts are more than me ... my ratio is even better!
me:time of registering: 05 Jun 2004 active members: 1409 members: 44617 posts : 36,105 Threads: 12,369 subject: all aspects of health
other forum:time of registering:16 Dec 2003 active members: 2,769 members: 131,759 posts : 789,108 Threads: 162,207 subject: computer and web programing
country - language - internet connection- software are similar