In a recent post I questioned the conclustions of an analysis of the Winter ratings that satellite radio had minimal impact on local radio, because persons using radio (PUR) hadn't changed overall. "Taint neccessarily so" says Arbitron. PUR includes terrestrial and satellite listening. The numbers reported by Radio Business Report (RBR) today shows a healthy trend upward in satellite radio's audience. Seems to me that an increase in satellite listening without an increase in PUR means that some local radio stations took a hit.
Years ago I was trout fishing on the Middle Fork of the Stanislaus River in the Sierras. The river, fed by heavy rainfall higher up, rose from mid calf depth to thigh depth in a matter of minutes without me noticing it. Luckily my observant wife on the bank suggested that I start paying attention before I got swept away in the current. If you don't pay attention and react to trends you could find yourself in over your head too .