Systematic Reviews

Role of the librarian in this stage

A librarian can advise you on quality assessment for your systematic review, including: 

  • What the quality assessment or risk of bias stage of the review entails
  • How to choose an appropriate quality assessment tool
  • Best practices for reporting quality assessment results in your review

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Types of bias

After the screening process is complete, the systematic review team must assess each article for quality and bias. There are various types of bias, some of which are outlined in the table below from the Cochrane Handbook.

Cochrane Handbook - Table 10.1.a: Definitions of some types of reporting biases

Type of reporting bias Definition
Publication bias The publication or non-publication of research findings, depending on the nature and direction of the results
Time lag bias The rapid or delayed publication of research findings, depending on the nature and direction of results
Multiple (duplicate) publication bias The multiple or delayed publication of research findings, depending on the nature and direction of results
Location bias The publication of research findings in journals with different ease of access or levels of indexing in standard databases, depending on the nature and direction of results
Citation bias The citation or non-citation of research findings, depending on the nature and direction of the results
Language bias The publication of research findings in a particular language, depending on the nature and direction of the results
Outcome reporting bias The selective reporting of some outcomes but not others, depending on the nature and direction of the results

Using Covidence for Quality Assessment

Covidence uses Cochrane Risk of Bias (which is designed for rating RCTs and cannot be used for other study types) as the default tool for quality assessment of included studies. You can opt to manually customize the quality assessment template and use a different tool better suited to your review. More information about quality assessment using Covidence, including how to customize the quality assessment template, can be found below. If you decide to customize the quality assessment template, you cannot switch back to using the Cochrane Risk of Bias template.

Systematic Reviews and Meta-Analyses

Clinical Practice Guidelines

Randomized Controlled Trials (RCTs)

Cohort Studies

Case-Control Studies

Cross-Sectional Studies

Diagnostic Studies

Economic Studies

Mixed Methods

Qualitative Studies