One of the most important aspects of the research process is evaluating the quality of sources in order to determine which provide reliable and useful information and which do not.

In order to select sources best suited to your purpose, you need to know what sort of information is required. For example, do you need general information, statistics, current data, biographical materials, or some other type of information?

Once you have located your materials, there are a few questions you can ask in order to evaluate the quality of a source:

• What are the author's qualifications? Is the author an expert in the subject or knowledgeable in the field being written about? For evaluating an author's credentials check one of the following:
  Contemporary Authors or Biography & Genealogy Master Index
• How current is the information? Check the book's copyright date or the publication date of the magazine in which the article appears. Some subjects, such as certain areas of science, change quickly. Other subjects, such as certain areas of history, may be covered adequately in earlier materials.
• What is the scope and treatment of the information? Examine a book's table of contents to get an overview of subjects covered. Read the preface and introduction to determine the author's purpose, the intended audience, the scope of the work, and the author's treatment of the subject. Periodical articles because of their relatively short length are often more tightly focused than books. Is there an indication of bias in the treatment of the material?
• What is the format of the book? Are there illustrations, graphs, or drawings? Is there an index to give easy access to specific information? Are other features provided that amplify the material, such as appendices or a glossary of terms?
• How was the book reviewed? Use book reviews to find out how the critics judged the book when it was published. Book reviews can be found in Book Review Digest (Z/1219/.C95) and Book Review Index (Z/1035/.A1/B6) located in the Gorgas Reference Index Area.
• If you are conducting research using magazine articles, it is important for you to determine what type of magazine you are using. Is it a scholarly journal, a popular magazine, or a trade journal? If you need help making this determination, please ask a librarian.