Evaluating sources

1. Use books written by scholars and scientists (is often mentioned in the book), preferably published by scientific publishers
2. Choose journal articles from peer reviewed journals (is mentioned in the  journal) over those in non-peer reviewed journals.

If you use other sources, it is extra important to check the scholarly level yourself. Of course, your source needs to be meaningful and relevant, above all.

The crux of science lies in the extent to which an author/researcher performs his work objectively and makes it verifiable. In determining the quality and scientific nature of sources you may start from three kinds of checks:

1. Check by others, preceding publication
   • editors: editors of scientific journals are stricter than editors of non-scientific journals
   • publishers: some publishers only publish scientific books
   • peer review: most scholarly journals but also some book publishers ask experts for a (single or double blind) judgement before publication
   • search engine/online bibliography: some search engines only include articles from high-quality, peer reviewed journals (for instance Scopus and Web of Science
   • financers: some journals demand to know who funded the research
2. Check by others, after publication
   • reviews (in the case of books): are the reviews positive?
   • citations (mainly in the case of articles): is the piece cited often (taking into account how long it has been available) and more importantly:what is being said?
   • open annotation and post publication peer review in systems like PubPeer and (for preprints) Peer Community In and comments at the preprint platforms themselves.
3. Check by yourself
   • are author and date of the text mentioned (particularly in the case of webpages)?
   • affiliation of the author: the author's job may tell you more about the scientific level, for instance if the author is employed by a good university
   • is the target group mentioned: (in particular in the case of websites and reports)
   • presence of explicit research questions and conclusions
   • presence of an explanation of the method used: how was the research conducted, where are the data coming from?
   • presence of enough and high-quality literature references or notes: what insights are used?
   • language level and well organised text

To determine if a publication or source is relevant, you can try to answer the following questions:

1. Does the source help you to answer your main questions and sub-questions?
2. Does the source answer your whole question/sub-question or only one aspect?
3. To what extent does the main question of the source you found match with your own questions?
4. How strong are the similarities between the research object or the analysis unit in the publication you found and those in your own paper/thesis? The research object may be a period, or a person, a group, an area, a substance, a disease, a process etc.
5. Is the context of the research object the same as in your case?
6. When was the source published and when was the research written about executed?

Think that you will rarely find a source that provides a complete answer to your main questions and sub-questions and that gives a report of the exact same research or problem you are working on.