Types of information sources

During your education you will use many types of medical information sources. Here are some examples of sources and their content.

Type of source	What characterizes this source?
Original research article	IMRaD structure, empirical study is conducted, is often peer reviewed.
Narrative review	Descriptive literature review that summarizes original research articles by others.
Systematic review	Review with a clearly defined method section describing searching and selection and quality assessment, compares e. g. effects of interventions
Books	Extensive research overview, may not be peer reviewed.
Dissertations	PhD thesis, may consist of several original articles.
Reports	Presents data or research results from governments, organizations, universities or corporations.
Conference abstracts	Short abstracts or posters, presenting preliminary results from new or ongoing research studies. May not be peer reviewed.
Websites	Here you can find guidelines, statistics and facts relevant for health care or patients.

Original research articles, systematic reviews and other reviews counts as research material, as these are published in research journals and are often peer reviewed.
Books can give an overview of a topic, but check the publication date. Additional research findings may have been published. Some books have been reviewed by an editorial group with expert knowledge within the field, but peer review is not required to publish a book.
Research publications is in focus during your education, and you will have training in how to find, assess, cite and use them.

Grey literature are papers, documents or literature that are not published in a research journal. They have not been peer reviewed in a traditional way, but may be authored by experts within the field.
Examples of grey literature can be dissertations, reports from organizations or authorities such as World Health Organization or United Nations, or preprints of research articles.
In some cases, data or study results are not available in traditional published research articles in journals. Grey literature can then be an important source for e. g. public health or basic facts or data in a specific topic.
Adding grey literature can decrease bias in your own project, as you add important sources of information not found elsewhere. But adding grey literature can also increase bias, since the documents are not peer reviewed. To address this, you can try to find information on how the data in the grey literature was collected, selected or analyzed (equivalent to the method section of a research article)