Whether you're using Google, a journal, or a book you found, it's important that you have the skills to critically evaluate the information that you find--your patients are depending on you!
If you think you can trust everything you find on the Web, just take a look at "Whales in the Minnesota River"!
The Utah Academic Library Consortium has put together terrific guide to critically evaluating information. Take a look at it, and try the online Web Site Evaluator excercise to test your ability to critically evaluate information.
