While some series are stable, others swing wildly in the rankings depending on the strength of each episode. When a series has no episode for a given week, the previous week's episode is used instead as a placeholder. The rankings indicate relative quality (A is preferred to B), not absolute quality (B is good/bad). While the titles are ranked from 'best' to 'worst', sometimes the difference between #1 and #10 can be very thin. If a series has no episode for a given week, we use the rating data for the previous week's episode in order to compute the weekly ranking.