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Health and Human Performance: Evidence Based Practice

Strength of Evidence based on Type of Research Study

Strength of Evidence Based on Type of Research Study

The type of study often determines the strength of the evidence and the relevance to real life. Meta-analyses and systematic reviews tend to have the strongest evidence. Intervention studies are often stronger evidence than observational studies. Non-human studies can provide insight and a foundation for hypotheses for stronger studies.

Types of research studies with strongest evidence at the top

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Research Tips

When you are searching, use keywords such as:

  • "systematic review"
  • "meta-analysis"
  • "randomized control trial" OR "RCT"
  • Look for the advanced search feature and sometimes there's even a filter for the type of research study

Types of Research Studies

Meta-Analyses & Systematic Reviews

Both methods combine multiple studies to summarize what is known about a topic

  • A systematic review reviews the studies that are already published about a topic
  • A meta-analysis combines the data and analyzes it as a group

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Intervention Studies

Examples: Randomized Control Trials (RCT) or Clinical Trials

  • Some type of treatment or change is imposed by the researcher, and then the effects of that change are measured.
  • Intervention trials CAN identify cause and effect if well-designed, such as randomized controlled trials.

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Observational Studies

Example: cohort studies, case-control studies, or cross-sectional studies

  • Make observations and look for correlations between different variables
  • No treatment or intervention
  • Can only identify correlations between variables
  • Correlation ≠ causation
  • Watch for confounding factors (factors that can affect the outcome in question)

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Non-Human Studies

Example: animal studies or in-vitro studies

  • Non-human studies are often cost-efficient and have high levels of control over the variables
  • While some results may occur in a lab, the context of a real-life environment may not yield the same results
  • These can serve as a proof of concept and a first step to informing further testing

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PICO

Using PICO to Create a Research Question

Using PICO, you could work through the patient, intervention, control, and outcome to generate the question "Is acetaminophen or ibuprofen more effective at reducing fever in children?"

patient, intervention, control, outcome: PICO

PICO narrows down your research question, helping you generate effective keywords for your search. Those keywords can be used in the advanced search feature to build a strong search query.

In the example below:

  • the asterisk (*) after child will bring up child, children, childhood, etc.
  • the synonyms fever or febrile or temperature or pyrexia yields more results (OR means more)
  • the synonyms ibuprofen or nsaids yields more results (OR means more)
  • pay attention to the suggestions of the database while you are typing
  • the plus sign at the end of the search box can be clicked to add additional rows or keywords
  • look for subject headings (or MeSH headings) within the database

advanced search in CINAHL using PICO keywords