Coverage
Here are some questions, written by Susan A.Gardner, Hiltraut H. Benham, and Bridget M. Newell in their 1999 article "Oh, What a Tangled Web We've Woven! Helping Students Evaluate Sources,” published in English Journal, that you should answer when determining the coverage of a source:
Is the scope of the topic clearly stated?
Why is this important? A reliable, credible source is going to be more reliable and credible if it handles a manageable aspect of the topic, rather than trying to cover absolutely everything about the topic. It is far easier to compile good information about a smaller aspect of a topic than it is to try to get good information about all aspects of the topic. For example, a site that covers every single aspect of every single one of Shakespeare's works would likely not be as reliable as one that focuses solely on Hamlet simply because of the sheer amount of information that would be required to give an accurate and reliable picture of each aspect of each of those works, whereas focusing on one specific work would make it easier to find and compile good information about that one work.
Are supporting materials (bibliography, charts, statistics, graphics, etc.) given?
Why is this important? As discussed earlier, if a site does not list its references or does not give any supporting materials, such as charts or graphics, then the site may not have credible information.
Are there links to other resources on the topic?
Why is this important? Again, as discussed earlier, if a site provides links to other sites on the topic, it demonstrates the author's knowledge of the topic and willingness to show and consider opinions and views other than his own.
Is the site still under construction?
Why is this important? If a site is under construction, then the site may not give an accurate portrayal of what the author intends to say. If the site has not been updated in a long while, it is likely that the information is also outdated and may no longer be accurate.