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Systematic Reviews

On This Page

  • Types of reviews
  • Systematic review definition
  • Systematic Review Compared to Traditional Review
  • Systematic Review Myths
  • Reducing Bias

Types of Reviews

Systematic Review Definition

This methodology prescribes explicit, reproducible, and transparent processes for collating the best available evidence in answer to specific questions.  In particular, it requires the use of robust techniques for:

  • searching for and identifying primary studies,
  • selecting the studies to be included in the review,
  • extracting the data from the studies, and
  • appraising the quality of these studies,
  • synthesizing the findings narratively and/or through pooling suitable quantitative data in meta-analysis

Dixon-Woods, M., & Sutton, A. (2004). Systematic Review. In Michael S. Lewis-Beck, A. Bryman, & Tim Futing Liao (Eds.), The SAGE Encyclopedia of Social Science Research Methods. (pp. 1111-1112). Thousand Oaks, CA: Sage Publications

Systematic Reviews / Traditional Reviews

Feature

Systematic Review

Narrative / Traditional Reviews

Question

Often focused (clinical) question.

Sometimes broad in scope.

Sources & Search

Explicit search strategy of multiple databases. Comprehensive sources.

Not usually specified.

Selection

Criterion-based selection; uniformly applied

Not usually specified.

Appraisal

Rigorous critical appraisal.

Variable.

Synthesis

Quantitative summary. Also qualitative/narrative.

Often qualitative summary.

Inferences

Based on all available evidence.

Based on a sample of the evidence.

Grading

All evidence is graded (quality)

May or may not be graded.

Adapted from: Cook, D., Mulrow, C. & Haydens, R. (1997)  Systematic reviews: Synthesis of best evidence for clinical decisions.  Annals of Internal Medicine,  126(5):376-380.

Systematic Review Myths

Systematic reviews:

  • are the same as ordinary literature reviews, only bigger
  • include only randomized controlled trials
  • require the adoption of a biomedical model of health
  • are of no relevance outside of health / medicine
  • must involve statistical analysis / synthesis
  • must be conducted by experts
  • can be done without experienced librarian support
  • are not really research

Adapted from: Petticrew, M.  (2001)  Systematic reviews from astronomy to zoology: Myths and misconceptions.  BMJ 322:98-101.

Reducing Bias

Systematic reviews attempt to minimize bias and error throughout the review process

  • Uses systematic process that is transparent and replicable
  • Clearly document transparent and replicable search strategies
  • Inter-rater reliability on key data
  • Assessment of bias in studies
  • Assessment of study quality
  • Meta-analysis (when possible) to statistically synthesize results across studies

 

Tanner-Smith, E. & SJ Wilson.  (2013) Systematic reveiwing for evidence-based practice: An introductory workshop.  The Campbell Collaboration.  

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