It is essential to evaluate all sources (print or electronic) before using them for an assignment or research project. Free online sources (websites) require more careful evaluation. The most common criteria to evaluate scientific sources are:
Who is responsible for the document or website, a person or an organization? Search for the author’s qualifications. Is it a government (.gov), an educational (.edu), a non-profit (.org) or a company (.com) website or document? Is it a popular or a scholarly source?
What is the content? Is it comprehensive and free of errors? Does the document or website include citations? If a website, does it include links to other good or reputable websites?
When the document or webpage was created or updated? Unless you are doing an historical background study, scientific information needs to be current, because it changes fast.
Why this document or webpage was created? Does it describe the purpose? Is the information balanced and presented with minimum bias? Biased information has its use, but you need to know that before you use it.