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Best Practice for Literature Searching

For the sciences of food and health

What is critical appraisal?

We critically appraise information constantly, formally or informally, to determine if something is going to be valuable for our purpose and whether we trust the content it provides.

In the context of a literature search, critical appraisal is the process of systematically evaluating and assessing the research you have found in order to determine its quality and validity. It is essential to evidence-based practice.

More formally, critical appraisal is a systematic evaluation of research papers in order to answer the following questions:

  • Does this study address a clearly focused question?
  • Did the study use valid methods to address this question?
  • Are there factors, based on the study type, that might have confounded its results?
  • Are the valid results of this study important?
  • What are the confines of what can be concluded from the study?
  • Are these valid, important, though possibly limited, results applicable to my own research?

What is quality and how do you assess it?

In research we commissioned in 2018, researchers told us that they define ‘high quality evidence’ by factors such as:

  • Publication in a journal they consider reputable or with a high Impact Factor.
  • The peer review process, coordinated by publishers and carried out by other researchers.
  • Research institutions and authors who undertake quality research, and with whom they are familiar.

In other words, researchers use their own experience and expertise to assess quality.

However, students and early career researchers are unlikely to have built up that level of experience, and no matter how experienced a researcher is, there are certain times (for instance, when conducting a systematic review) when they will need to take a very close look at the validity of research articles.

There are checklists available to help with critical appraisal.  The checklists outline the key questions to ask for a specific study design.  Examples can be found in the Critical Appraisal section of this guide, and the Further Resources section.  

You may also find it beneficial to discuss issues such as quality and reputation with:

  • Your peers
  • Teachers
  • Your principal investigator (PI)
  • Your supervisor or other senior colleagues
  • Librarians
  • Journal clubs. These are sometimes held by faculty or within organisations to encourage researchers to work together to discover and critically appraise information.
  • Topic-specific working groups

The more you practice critical appraisal, the quicker and more confident you will become at it.