As you get information from your various sources, critical judgment is needed to understand the value of each piece of information. Aristotle wrote 2300 years ago that an audience judges a speaker on three criteria: competence, trustworthiness, and good will. These criteria work pretty well for judging whether you should use information in a paper or a speech today. If you hold an article in your hand, ask yourself three questions: How competent is the author of this information? Can I trust the author to have been honest and thorough in giving me the information? What motives does the author have for writing this material in the form it is in?

If you read a lot of books on evaluating evidence, you'll find some common standards that echo these criteria:

• Credibility: Can the source of this evidence be believed?
• Authoritativeness: Does the author have the knowledge needed to make this information reliable.
• Audience attitude: Will this source and this information be acceptable to the reader who will read your essay or paper?
• Recognizing bias: Is there a bias in the source? Of course, Republican legislators will endorse Republican candidates for Governor! The point isn't that you have to disregard information because the source may have a bias--it is that you have to consider what influence that bias may have on the truth.  In some sense, all sources have a bias.
• Timeliness: There is an important connection between time and events. A book on the plight of the migrant farm worker written in 1946 may have compelling stories within it, but how pertinent are these stories to the condition of farm workers in 1998? Again, there are many uses for the 1946 book, including a study of the history of farm workers and problems in California agriculture, but the link between the 1946 facts are 1998 conditions would need to be established.
• Pertinence and appropriateness to assignment, subject focus, speaker/writer, and audience.