I don't know. I can only guess that they go by subscriber feedback. I figure they probably keep track of which stations are being listened to via the internet. But the entire Sirius lineup isn't available on the web. I voiced my displeasure with them for replacing channel 10 "The Bridge" with "E-Street Radio." All Springstein, all the time. Nothing against "The Boss." But I wasn't happy with the replacement of a channel I listened to daily, with one I will likely never listen to.