How are top anime/manga scores calculated?
Only scores where a user has completed at least 1/5 of the anime/manga are calculated.

Example: If you watched a 26 episode series, this means you would had to have watched at least 5 episodes (26/5.2)=5. We're using 5.2 instead of 5 so we get a whole number for "most" series.

Weighted Rank (WR) = (v / (v + m)) * S + (m / (v + m)) * C
S = Average score for the Anime (mean).
v = Number of votes for the Anime = (Number of people scoring the Anime).
m = Minimum votes/scores required to get a calculated score (currently 50 scores required).
C = The mean score across the entire Anime DB.

Top Upcoming and Most Popular ranking calculation
The Top Upcoming and Most Popular titles are calculated differently to above, and are instead judged by popularity.
This popularity is measured according to the number of users who have the title in their list. The more users that have the title shown in their Anime or Manga list, the higher it will be ranked.