Sometimes, you will have to use sources that are not scientific, such as for example reports, webpages or blogs. If you use a source that has not gone thru peer-review (i.e. there is no formal quality control), you must judge the quality and reliability yourself. Here follows some advice on what to consider when evaluating a source.
It is important to remember that all material has a sender, a purpose and a target. The first thing you need to establish is who the sender (i.e. the author) of the source is, and if they have authority in the field in question. Remember that the author is not always a person, it can also be a public authority, an organization or a company. You might also want to look at the provider of the source, to see whether there is a recognized publisher, authority or organization behind the information.
The next step is to determine the purpose of the source and for whom it was intended. Beware of information published by for example companies or lobby organizations, or if you have other reasons to suspect that there could be political, economic or personal motives behind a source. To evaluate the relevance of a source to your needs, you can also be helped by looking at the intended recipients. Information directed at researchers or students might be more relevant than if it is targeted at the general public or a consumer group. Make sure that the sources you use are fit for purpose.
Last, but not least, you should evaluate the credibility of the information itself. You need to validate the facts and whether text is written in an objective manner. Beware that, even if there are no factual errors, an author can choose to present a subject in a way that is biased. You also want to evaluate to what extent the source covers the subject and if the material is sufficiently current for your needs. Finally, you should look at the number and type of references given.
Evaluate your informal sources using the checklist below. Use your own judgment and be careful!