Playboy,  which has periodically ranked "party schools," announced Friday it would issue such reviews annually, potentially setting up a challenge with Princeton Review,  whose guidebook is best known for its party school rankings. The differing methodologies of the two operations result in different "winners" of the competition that most administrators would prefer to lose. Playboy does include learning as one factor in its rankings. The other four factors are: athletics, campus life, availability of sex, and a "bikini index," based on weather, female-to-male student ratio, and cheerleaders. The resulting top five for Playboy: University of Miami, University of Texas at Austin, San Diego State University, University of Florida and University of Arizona. The Princeton Review bases its selections on student surveys covering the use of alcohol and drugs, hours of study a day and the popularity of the Greek system. The Princeton Review's current top five are: University of Florida, University of Mississippi, Pennsylvania State University, West Virginia University and Ohio University.