A peer-reviewed journal is a special type of journal where articles are reviewed and selected by other academics and researchers prior to publication.
Peer-reviewed journals are often called research or refereed journals because they typically contain research results and reviewed articles for a specific scholarly field or discipline and have undergone a formal review process.
Peer-reviewed journals are an excellent example of scholarly sources of information.
(From Library Lingo, Colorado State University Libraries http://lib.colostate.edu/lingo/p Accessed March 7, 2011)
The quality of your information sources affects the quality of your research - the conclusions you draw, the material you use to support them, etc. Traditional information sources are in some ways easier to evaluate than online sources because more often than not you are dealing with established publishers, indexing & abstracting services, etc. In contrast, there's a vast amount of uncontrolled information native to the web that gets posted every day.
How reliable is the information? Are there editors and fact-checkers? (Anyone can publish on the web and there are no standards to ensure accuracy.)
Who are the authors? What are their qualifications?
How reputable is the publisher, if indicated?
Is the information presented with a minimum of bias? Is the identification/aim of the author/group clearly stated, if at all? (Be alert to the fact that the Web often functions as a "virtual soapbox".)
Is the content up-to-date? Is the publication date clearly labeled?
(Dates are not always included on Web pages. If they are, do they mean the date the information was written, placed on the Web, or last revised?).
What topics are included? And are they explored in depth?
(Be careful: Coverage may differ when printed material moves to the Web.)
Think about your research question. Does the source truly address your research question? Consider the source's time period, location/geography, and population.
What are the author's credentials? Is he or she an expert in the field you're studying? Is the publication a respected one? What defines "reliability"? Most scholarly/peer-reviewed sources are reliable. Many internet sites from government agencies and universities contain reliable data & information. However, many popular magazines and internet sites (for example, Wikipedia) cannot be considered reliable (the dynamic nature of Wikipedia prevents us from being able to guarantee that we'll be able to find the source again if someone else updates the page or changes the information). Think about the authors and their credentials.
Do you need recent information? Is the source recent enough? If you're writing a paper about smart phone technology, you'll want to use very recent research to support your topic. A source from the 1960s would not be appropriate for this type of research.
Johns Hopkins University Library: Evaluating Information Found on the Internet: http://www.library.jhu.edu/researchhelp/general/evaluating/