April kicks off with 14 games shrinking in terms of monthly active users and 15 with fewer daily active users than they enjoyed a month ago. Between the two charts, generated using AppData‘s Top Applications Leaderboard, we see that Mafia Wars sits higher in MAU versus DAU as the result of a late month cross-promotion campaign in CityVille. On the day the campaign launched, Mafia Wars hit a high of nearly 5.6 million DAU compared to its April 1 showing of 2.3 million DAU.

We find that drawing overt conclusions from shifts in our top 25 Facebook games by DAU presents some challenges. While the DAU is generally a better measure of a game’s engagement and monetization potential, it’s also vulnerable to external factors in a way that MAU is not. For example, we watched CityVille’s DAU dip around the week of March 15, reaching a low of 19 million on March 22 before creeping back up toward its April 1 level. A possible explanation for this fluctuation is that this period of March is about the time when most schools in the United States go on Spring Break; and how many people really play CityVille on vacation? Or on weekends or holidays when kids are home from school? Note that we saw this possible DAU “Spring Break dip” throughout most, but not all, games in our top 25 games by DAU.

Second, a DAU count does not always factor in a game’s intended play cycle. For example, a player only needs to play Zuma Blitz once a week to maintain a presence on the leaderboards. Additionally, developer PopCap Games features a community-oriented video only on Mondays, which may explain some of the zigzags we see when viewing Zuma Blitz’s DAU flow for the month. Third, and perhaps most difficult to interpret, how do factor out the percentage DAU that comes from the heavy user influx spurred by an ad or cross-promotion campaign? An example would be the spike Mafia Wars enjoyed as a result of the CityVille cross-promotion; if we attempted to take an average DAU for the entire month of March or if this campaign happened to fall on April 1 instead of March 20, this one-day spike would’ve skewed the game’s DAU ranking significantly.

We’d love to hear your ideas on how to address the challenge of accurately representing a game’s DAU for our monthly top 25 articles. For the time being, we’ll compare first-of-the-month numbers between titles on the rankings list just as we do for the MAU list.

All results of our Top 25 articles are based on information collected from AppData, our traffic tracking service for social games and their developers.