HERE IS AN INTERACTIVE TUTORIAL ON AUTHORITY:
As you identify resources on your topic, it is important to evaluate each resource for quality. If you have selected articles from scholarly and peer-reviewed journals, you can be fairly certain that the content is accurate, objective, and written by an authority in that field of study.
Image: (CC) J. Bouma: http://www.flickr.com/photos/jakebouma/3345296623/
If you locate information on your topic using a Web search, you'll want to be especially attentive to factors that will indicate whether or not the information is reliable. A web site can provide a number of clues about the quality of its content, so it is important to critically evaluate every resource you locate on the open Web.
There are a number of different approaches to evaluating articles and web sites for quality. Most include considering the accuracy, authority, objectivity, and currency of information. Consider using the CRAAP Test (Currency/Timeliness, Relevance, Authority, Accuracy, and Purpose).
View video on How Library Stuff Works: How To Evaluate Sources (the CRAAP Test) OR ANOTHER ON THE CRAAP Test in Action: Websites.