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Nursing

Critical Appraisal Tools

Types of Evidence

Article Type Definition Evidence Level
Systematic Review A study of primary research articles centered on a clinical question. Include explicit methodology about how the authors conducted a comprehensive literature search and appraised the included research. Very High
Meta-analysis A type of systematic review that synthesizes the results of multiple studies based on statistical analysis of the individual results. Very High
Randomized Control Trial Study subjects are randomly assigned to experimental or control groups and are followed over time to observe the outcomes/variables. Studies are often "blind" or "double-blind" to reduce bias. High
Quasi-experimental and Experimental Nonrandomized intervention studies that often use a pretest-posttest model to measure the intervention. May or may not be controlled. High
Cohort Studies Observational studies that compare outcomes in two groups of individuals over time. Participants in each group share characteristics (such as demographic, occupations, etc.) but differ in exposure to the specified determinant (e.g. smokers vs. non-smokers). Medium
Case Control Studies Compares a group that has a condition/disease (case) with a group that doesn't (control) to investigate if characteristics or past exposures determined a certain outcome. Medium
Qualitative Studies or Systematic Reviews Qualitative research uses a participant's own words and their perceptions of experiences or phenomena. Data are analyzed by theme or theory rather than by logically or statistically. Low
Case reports, Editorials, Expert Opinion Case reports: reports on a small number of patients (usually one) with a certain outcome.
Editorials: reflect the opinion of the editor of a publication typically commenting on published article or current issue; editorials should draw from objective analysis; editors may invite an outside expert to write the editorial.
Expert Opinion: commentary from a credentialed or experienced authority; may or may not be based on objective analysis; may or may not be published in an academic publication.		 Very Low

Important Note: Evidence that is lower on the scale can still be important to your research and may add valuable context to your argument. Just make sure you supplement it with evidence that is higher up the scale.

Primary vs. Secondary Research

Primary or Original Research

Reports on an empirical study conducted by the authors of the article. Almost always published in peer-reviewed journals.

  • Can be quantitative (reports numerical data, uses statistical methods) or qualitative (reports on situational themes, uses observational methods)
  • States a research question or hypothesis
  • Has a section called "method" or "methodology" that describes a specific research method
  • Written by the researchers who conducted the study

Examples include: Randomized Controlled Trials (RCTs), cohort studies, case control studies, case reports

Secondary Research

Evaluates or summarizes research conducted by others. May or may not draw conclusions from the included original research.

  • May answer a clinical question or provide practice recommendations or guidelines
  • May include statistical analyses of combined study results (called Meta-analysis)
  • Often includes a section describing authors' methods for finding and selecting studies
  • Might not be peer-reviewed depending on the type of publication

Examples include: Systematic Reviews and meta-analyses, clinical practice guidelines, editorials or expert opinions, book chapters, literature reviews

 

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