Thanks for clearing my doubts. In this case i will just concentrate on posting quality posts rather than post quantity. i hope i will be winning the member of the day at least once! Anyway, I still didn't find much time to post there, as i am busy with other forum..
Though main factor is quality of your post, it also depends upon the number of competitors or contestants. Suppose if you make 10 quality posts, but one more member has made more than 15 quality posts, then you will not be selected as a winner. So it is purely upon the number of competitors. I have won the contest even when I made just 6 posts, and sometimes I haven't won even when I made 30 posts.