Consider the following factors when you evaluate sources.

Factor one: Relevance and Content

For first question to ask is whether or not the source is pertinent to your research. That may seem obvious, but it isn't also easy to tell immediately. Try to determine the main point of the source, but also the depth and breadth of its coverage. If a source treats your topic extensively, you can easily decide to hold on to the source for further examination. If it only marginally covers your topic, however, it may still be useful. You just have to look harder. Only one section or one page or one paragraph may be directly related to your topic, but it may address a viewpoint that you might not otherwise find.

Once you determine that it is relevant, then you need to figure out the quality of its content. Remember that you need to find several sources that represent several different points of view. Just by looking at a source, you should be able to determine quite a few important things, but to evaluate any one source well it will also be necessary to look at several different sources and look beyond just what you read on the page.

• From the language used and arguments made, you can probably have a good idea whether or not the author is being objective and reasonable. Clever writers can hide their biases, and all writers will have different points of view, but their arguments need to be clearer stated, reasonable, and well researched. Authors should explain what evidence they have found to support their conclusions.
• Although it isn't easy to separate fact from opinion, it is important to try. Some people argue that there are no "facts," only someone's interpretation of facts. To verify what has been written, it is important to compare one source with another. Do they agree or support each other? Even if the authors' ideas are new, do they seem in line with other things you have read? Does it appear that the authors are avoiding or omitting information that doesn't support their arguments. Unless an author has something new to share, there is little point in writing, but if what is new radically departs from everything else you have read, you need to analyze the conclusions even more carefully.

Factor two: Type of source and the intended audience

The type of source is usually related to the intended audience. Popular sources are principally written to entertain and inform a general reader. Scholarly sources are intended as a means of researchers or professionals to exchange ideas. So in determining whether a source is popular or scholarly, you can better tell how useful it will be to your research.

The difference is important for a couple reasons. A popular source may be easier to read, but to adequately address many topics of research, a certain level of complexity in writing may be required. Talented writers can better make in depth topics easier to understand, but to simplify a topic to the level an eighth grader can understand, important aspects are probably being left out. If the source was written to entertain or advocate a particular viewpoint, it is a much different in usefulness and value than one that is principly designed to inform or report on scholarly or scientific endeavor?

• If the source is a book, check who the publisher is. As an undergraduate, you probably don't know the quality of diffferent publishers, but some are well known for publishing in certain academic disciplines and have better reputations than other. One easy thing you can do is check if the publisher is a university press or an scholarly society. That doesn't guarantee the quality of the material, but it does assure you it is an academic publication.
• If the source is a periodical, is it a magazine or journal? If you need help in figuring out what kind of periodical it is, see this chart explaining the different types of periodicals.
• For some research projects, it is important to use primary materials. Primary sources are raw materials, such as original materials. In sciences and social sciences they are often the reports of original research projects that are found in scholarly articles or papers delivered at conferences. Secondary sources are comments on or interpretations of or discussions about primary sources.

Factor three: Author

It is important to determine an author's credentials, but what does that mean? Perhaps a simpler question would be, "What do you know about the author, and why should I believe this person when she or he is writing about this topic?" Unfortunately just because a person is writing about a subject, that doesn't mean she or he is an expert. Does this person have any academic background or other expertise that qualifies her or him to write in this field? Some journalists explore one type of topic for a long time and become extremely knowledgeable about it, but others are staff writers who may be given an new assignment because she or he is available, not because of any prior knowledge of the topic.

• To find out about an author, the first place to look is the source itself. Books often include some biographical information about the author in an introduction or preface or at the back of the book. Information is also included on a book jacket, but, unfortunately, college libraries typically throw book jackets away. A scholarly journal will list minimal information about authors, but they will include their institutional affiliation (usually the college or university or research institution where they work or teach).
• If you can find authors' names in biographical sources, such as Who's Who in America or Contemporary Authors, you can usually find something about their educational backgrounds, expertise or interests, and what else the authors have written.
• Another simple way to find out what else the authors have written is to check the online catalog or Amazon.com for books, and periodical databases for articles. Numbers of books and articles written doesn't necessarily mean much, so also check what subjects they have tackled and what kind of publications they are found in.
• Book reviews might tell you a little about the author, and they will certainly tell you what others think of their writing. Researchers will more often exchange ideas in journal articles than books, so this may be an even better clue as to the expertise of an author.

Factor four: Timeliness

How old is the information? Is the information up-to-date and accurate? For your particular research, is using older materials appropriate? If an article about a current event has been written recently, does it cover the event objectively?

For books you can check to see if it is a first or later edition. If there are more than one editions, a later one almost always should be preferred, since it will have been revised and updated to "improve" on the earlier edition to make additions or corrections. Most books will only have one edition, but if there are many printings that could be a clue that this source has been well received. If it is an older work with many printings it may be a standard source. Unfortunately just because an older book can still be found in the library that does not mean that it is a reliable source.