It might surprise you to know that public stations (like 'HYY, 'RTI, 'XPN, etc) really don't care much about ratings. I mean, it's nice to know how you're doing relative to the market in general. And maybe we'll use them to consider some schedule adjustments to stabilize or gain more "core." But it's not like we're out there selling the numbers. Public stations are more concerned with loyalty and affinity on the part of listeners. We're looking to make sure we're serving our core audiences properly, and that the core either stays stable or grows. We really don't care how old our listeners are, just how loyal they are, and whether, and how much they value our service. And the numbers are somewhat meaningless because, as someone said, our fund drives don't do us any favors (except bring in a nice chunk of operating income).
As for the liberal vs conservative thing, NPR, and public talk radio in general is actually quite balanced. People have two main misconceptions about public talk radio. We're either too (pick a side), or we're all gay.
The "gay" thing comes from the actual sound of our talk stations--FM, less processed, very midrangy. Sort of makes us all sound like we're lisping. Craig Ferguson recently had a funny, joking exchange with NPR's Peter Sagal that may have been more revealing than anyone may have thought. Look it up on YouTube if you get a chance (it was on Craig's CBS-TV show).
As for the left/right situation: besides the independent research that says we're pretty much balanced, for every complaint we get locally that we're biased to one side or one issue, there's a complaint that says we're on the opposite side. And left/right isn't the worst of it. You should see what we get when the Top-'o-the Hour NPR Newcasts report on the Israeli/Palestinian troubles. Even the music stations that run the NPR 'casts get hit with that one. Sheesh, you'd think our listeners, who it's true are more affluent, better educated, better read, with a broader worldview, would put their big brains in gear before putting their mouths and pens to the gas pedal! It's almost like they're reacting to Rush or Stern or someone.
In any case, this is probably too way off for the subject at hand, but I thought it might be nice to get it all out there.