All sources are not created equal. When we read that sentence, we think, "Well, of course! That's obvious." But when doing college-level research, students frequently forget that sources they retrieve may not be suitable. Sources might be non-scholarly, lacking authority, simplistic, irrelevant, extremely biased, or just plain wrong. It's important that you critically examine every source you intend to use in your research project.
With each source, ask yourself this question. If I make an assertion or claim, am I confident the content of this document authoritatively backs me up? Or, to put it another way. If your professor says "prove it!" can you confidently point to this document as proof? The following criteria will help you decide.
You may not know who the important authors are in the field, but there are some clues to look for. Is the person employed by a prestigious institution? Are the person's academic credentials relevant to what he/she is writing about? Is the book published by a prestigious publishing house? Is the journal peer-reviewed? If you can answer "yes" to any of the above questions, chances are great that the content is authoritative. If you can't answer "yes" to any of the above questions, the source may still be good, just not topnotch. Check out the other evaluation criteria below.
Everyone writes from a certain perspective and is, therefore, biased. However, bias can be charted on a continuum. Some sources are so biased that facts are distorted or ignored. Look for words or phrases that signal bias, such as, inflammatory or unverifiable statements. You are looking for authors who have seriously wrestled with the issues and who at least respect opposing viewpoints.
While you may not find sources that cover your topic exactly, you should only use sources that are relevant to your work. Don't pad your bibliography with irrelevant sources. Does the source provide a new or different perspective? Does it support your position? Is it a viable opposing view to which you should respond? Is the information current?
Always choose the sources that take the time to carefully lay out the issues. The number of words is not the issue here; a two-page article may be more comprehensive than a 10-page paper. Look for how well the author has mastered the subject.
What you're looking for are the best sources to back up your claims and assertions. When you declare something to be fact or provide an analysis of an event, you need the words of an expert to add weight to your declarations. Don't settle for the first couple of sources you find - the authors might be ignorant of the subject and the content worthless!