<p>This kind of system is flawed for one large reason:</p>
<p>It tends to be bimodal in its data. If you go to rate a professor, you either really really loved him, or really really loathed him. It's good as a way to gauge if the guy (yes, I'm being gender specific, sue me...) is a tyrant and horrifically bad, but my experience with these things is that they're usually as inaccurate as a drunk French soldier. (Oh snap, makin' with the French jokes? Is this guy fo' real?!)</p>
<p>Seriously though, use these at your own risk.</p>