Internet resources cannot be taken at face value. The researcher must evaluate Web sites/pages for scope, authority, content, and currency. These criteria are essentially the same used to evaluate traditional print resources. There are some adaptations for the online environment.
Is the purpose of the resource clearly stated? A site's purpose should be clear and its content should reflect its purpose, whether it's to educate, persuade, entertain, or sell. Is the site appropriate for the intended audience? Is the site for a subject expert, a layperson, a school student? How does the site compare with other sites on the same subject?
What items are included in the resource? Is the scope only implied, or is it stated through metainformation such as an introduction? Does the actual scope of the resource match expectations? Aspects of the scope include:
Who (person or agency) is responsible for the content? What are their credentials? Why should we believe what they say? Is the person/agency objective, or do they show a bias?
What are the author's reputation and qualifications in the subject covered? Are sources of information stated? Can the author be contacted for clarification or to be informed of new information? Examining the URL can give clues as to the author's relationship to the organization. For instance, a tilde "~" often indicates a personal Web directory, rather than part of the organization's official Web site.
If the resource is fee-based or selling a product, is there substantial content offered for free? Is the information on the site accurate? Is the information factual or opinion? Ask "why is the author placing this information on the Internet?" Frequently the answer is that the information is placed to advertise or support a particular point of view. Does the site contribute something unique to the subject? How current is the information? How frequently is the resource updated? Are dates of update stated? Browsers may allow you to view the date of creation and modification of a file [in Netscape View|Document Info]. Remember this may not be the date that the actual information was created or reviewed. If there are links to other sites, do they work? Are they appropriate? Is the content well-written (easy to read, correct spelling and grammar)?
Is there any bias in the content?
Is the information fact or opinion?
Does the site contain original information or simply links?
Does the site consist of internally maintained links or does it consist of external links over which there is no control?
Is currency important to the topic of the site/page?
When was the Web item produced? When was the Web item mounted? When was the Web item last revised? How up to date are the links? How reliable are the links; are there blind links, or references to sites which have moved? Is contact information for the author or producer included in the document?
It is increasingly common to see Web sites that have not been updated for years. This "Internet deadwood" should be evaluated with special attention.
If a Web page or documents has vanished "without a trace," try recovering it from the The Wayback Machine.
Additional information on evaluating Web pages can be found on the University of California, Berkeley Library Web page entitled Evaluating Web Pages: Techniques to Apply & Questions to Ask. Of special interest on that site is the Web Page Evaluation Checklist.