Up until about six years ago, Nielsen derived its radio ratings from diary surveys that listeners filled out based on their weekly tune-in. While these diaries remain a vital way of capturing radio listening for many markets, Nielsen now has 48 markets where portable people meters electronically capture listener consumption over a 28-day period. Despite the differences between these two methodologies, however, one thing is clear: every day counts for broadcasters who are trying to maximize their audiences. Peak listening across the country happens at the end of the week, and stations can always find ways to tweak their programming to boost listenership.