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Nursing Experts: Translating the Evidence - Acute & Ambulatory Nursing Care

Appraisal Concepts - Validity & Reliability

What is validity?

Internal validity is the extent to which the study demonstrated a cause-effect relationship between the independent and dependent variables.

External validity is the extent to which one may safely generalize from the sample studied to the defined target population and to other populations.

What is reliability?

Reliability is the extent to which the results of the study are replicable.  The research methodology should be described in detail so that the experiment could be repeated with similar results.

Scientific Experiment Terminology

  • Hypothesis - a statement that is believed to be true but has not yet been tested.

  • Independent variable - the component of an experiment that is controlled by the researcher (for example - a new therapy).

  • Dependent variable - the component of an experiment that changes, or not, as a result of the independent variable (for example - the existence of a disease). 

  • Bias - prejudice or the lack of neutrality.  A systematic deviation from the truth that affects the conclusions and occurs in the process or design of the research.

  • Confounding - a mixing of the effects within an experiment because the variables have not been sufficiently separated.  Possible confounding variables should be discussed in the report of the research.

See also Study Design Terminology from the Levels of Evidence tab in the EBM Guide

Sample Questions for Evaluating a Study

Large blue question mark

  • Has the study's aim been clearly stated?
  • Does the sample accurately reflect the population?
  • Has the sampling method and size been described and justified?
  • Have exclusions been stated?
  • Is the control group easily identified?
  • Is the loss to follow-up detailed?
  • Can the results be replicated?
  • Are there confounding factors?
  • Are the conclusions logical?
  • Can the results be extrapolated to other populations?

Online Appraisal Resources:

Is the evidence sufficient to warrant a practice change?

Once you have gathered and appraised your evidence, you will need to decide if the evidence warrants a change in practice. You will want to look at the "body of evidence" to make your determination - not just one study.

  • You may find the evidence does not suggest a change. That can be frustrating, but it is useful to know that your current practice is the standard
  • You may find that there isn’t evidence and a research study may be needed. That is beyond the scope of this project. You may wish to contact your nearest university with a nursing PhD program and suggest this as an area of research that is needed.
  • How do you determine if the evidence is sufficient?
  • If the evidence appears sufficient, you are ready to move to Translating the Evidence
    • If you found a Clinical Practice Guideline, a good quality Meta-Analysis, or more than 2 Randomized Controlled Trials with consistent results, related to your question, it's likely that you should pursue a change
    • If you found good evidence (perhaps not high level) with consistent results, evaluate  the risks and benefits as the results would apply to your patient population
    • If you found conflicting results, you may decide to delay a change, and track the literature for new evidence, or consider contacting a PhD nursing program to suggest this as a topic of research.