Evaluating sources

If you also want to use information from websites other than regular scholarly articles and books you should be extra careful and think about the role you give that information in your argument or analysis.

Ask yourself the following questions when reading webpages and be extra careful if the answer is negative most of the times.

1. Is the name of the author/maker available (and do you know more about the author or organisation)?
2. Can you find an e-mail address of the author/maker?
3. Is the webpage free of (lots of) advertisements?
4. Is the use of language careful, not childish, correct?
5. Is it clear how the information on the page came about?
6. Are sources mentioned (so no phrases like "research shows that") without any quotation of sources?
7. Are claims well-founded (so no phrases like "as is common knowledge")?
8. Is it a balanced piece or does all information point in the same direction?
9. Is the author open about matters still unknown or uncertain?
10. Can you find when the page was written or updated?
11. Is the page unbiased or in any case without strongly political or commercial aims?

The various types of databases and search engines differ in their scientific reliability.

General bibliographic databases: scientifically reliable

• There are general bibliographic (and citation) databases (e.g. Scopus and Web of Science) that only contain scientific material and peer reviewed articles in all disciplines.

Subject-specific bibliographic databases: scientifically reliable

• Subject-specific bibliographic databases (for instance PsycINFO, PubMed, Historical Abstracts) attempt to make scientific material in a particular discipline as broadly searchable as possible.

Large hybrid general search engines: scientific level not guaranteed

• Umbrella search systems such as Google Scholar are less trustworthy as to scientific quality, because the selection criteria are fairly crude and partly technical by nature. Many sources and databases are included so there is no certainty whatsoever about the scientific level

University library catalogues: scientifically relevant

• Material in university library catalogues is included because of its relevance for education and research of the university in question. This means that the catalogues may contain non-specialist and non-scientific sources which are nonetheless relevant.

The criteria for selection and inclusion applied by a particular search engine may tell you something about the basic quality of the sources included.

What are the criteria used in search systems?

• Citations: the more often a particular source is cited, the better this source is represented in the search system. In such cases a citation is viewed as a kind of voice for the quality of the source. For instance in Web of Science citations of a source are an important criterion for selection and inclusion
• Advice of a 'content selection & advisory board': Some search engines include sources based on the advice of a group of experts. For instance Scopus and Web of Science.
• Peer reviews:  search systems may use peer review as a condition for including sources. This is the case for most scientific search engines. Peer review (blind or half blind) means that articles are presented to experts before publication. In this way a minimum of scientific quality is guaranteed. However, this does not mean that articles from peer reviewed sources are always better than the ones without peer review.
• Relevance:  library catalogues and subject-specific search engines include sources because of their relevance to education and research for the institution or discipline in question.
• Technical criteria: several search engines apply technical conditions for including sources. For instance Google Scholar also uses an automated system that recognizes texts as being scientific based on several elements.