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Evaluating sources: Get going

Evaluating: an introduction

The sources you use when writing a scientific text (such as a thesis, paper, etc.) largely determine the quality of that text.

Before you use the sources you have found their relevance and scientific nature should be evaluated. In this Libguide we will offer you several methods and tools.

Critical reading

Even if you do all the checks on these pages there are no guarantees that the texts you will be reading are true, objective and unbiased. You will always have to pay close attention to the sources you use. And above all, always remain a critical reader.

How to determine the scholarly nature of sources?

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

How to determine the relevance of sources?

klik voor maker van deze animatieTo 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. 

Rules of thumb in using sources

  1. Peer review: controle door wetenschappersUse 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.

Find out more

Using non-scholarly sources or grey literature

For non-scientific sources (newspapers, blogs, websites etc.) and so-called grey literature (e.g. master theses, dissertations, reports, statistics, policy papers), pay close attention to:

  1. the author or responsible organisation
    1. is the author well-known and what are her/his qualifications?.
  2. the publication date or the date when the source was updated
    • is the website up to date and properly maintained?
  3. the purpose of the source
    • What is the intention of the source (promoting products, influencing opinions)? What is the target group (scientists, a specific group (for example patients), the general public)? 
  4. the quality of the source
    • look at the use of language, the level of argumentation (are facts, figures and claims sufficiently substantiated?) and the literature references

See to the information on evaluating websites or use the CRAPMAP to make sure that you can use a website as your source.

You can use non-scholarly sources:

  • as object of research (eg how is something discussed in popular media)
  • when scientific research is not yet available
  • as primary source (archive records, letters, interviews, statistics, news items etc.), to be used as documentation or factual material
  • as indication of social relevance
  • as illustration to your subject

See also the  LibGuide on the use of Wikipedia in science.