There are two methods we use at Etown to evaluate sources: CRED and the CRAAP Test. With both of these methods, you look at a set of specific elements and use these to determine if your source is of acceptable quality to use for your project.
C - Creator
R - Resource
E - Errors/Accuracy
D - Date
C - Currency - When was the source published and does the date of publication meet the needs of the research topic?
R - Relevance - Does the information in the source directly apply to your research and help to support your thesis or research question?
A - Authority - This is an important one when looking at online sources. Is the author / authors an authority on the topic? Is the publisher of the information trustworthy and reliable? If you aren't familiar with the publication or website, you should do some quick research on it to make sure it is a professional publisher. If the resource doesn't appear to be professional, could you find a better source elsewhere online or from a database?
A - Accuracy - Does the source cite or link to research that backs its claims or arguments? Are those resources also reliable or trustworthy?
P - Purpose - Is the source meant to inform or is its purpose to sell something or to entertain?
The CRAAP Test was developed by Meriam Library at California State University, Chico and is sharable via a CC License.