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Systematic Reviews

A guide directing researchers on the systematic review process. Layout based on Doing a Systematic Review: A Student's Guide, 2nd Edition, by Angela Boland, M. Gemma Cherry, and Rumona Dickson.

Quality Assessment

Now that the body of literature has been compiled and data has been extracted, it is time to assess quality of the studies reviewed for relevance to the research question.


Evaluating for Bias

When reviewing study quality, assessing for bias is necessary to ensure reliability. Biases to assess for include the following, to name a few (Boland, Cherry, & Dickson, 2017):

Selection Bias

How generalizable are the results of the study to your target population?

Is the sample representative?

Allocation Bias

How were participants assigned to treatment groups?

Is this a predictable assignment, or was it random?

Performance Bias

Were participants and/or researchers aware of their treatment group assignment?

Were studies single-blind? Double-blind?

If participants are aware of their assignment, they may feel an obligation to perform a certain way in alignment with the study's goal.

Detection Bias

Were data analyzers and those reviewing study outcomes aware of individual identities/treatment group assignments?

This may bias study results.

Attrition Bias

What portion of participants stopped treatment prior to the end of the study?

Did participants dropout of the study, withdraw, or not meet inclusion criteria?

The more participants that drop out, the less generalizable the results.

Reporting Bias

Were all outcomes reported on?

Did authors fail to report outcomes that did not hold significance?

Assessing Study Quality

When assessing for quality, there are numerous tools available for researchers to use. See the following resources for more information.

Assessing the Systematic Review for Quality

The following are standard tool used for quality assessment. Note, AMSTAR and PRISMA are standards in assessing systematic reviews, while MOOSE is the standard for assessing meta-analyses.