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NSG325: Psychosocial Nursing: ACQUIRE: Search for Evidence

Course Guide for NSG 325

Research Process

The search for best evidence should first begin by considering the elements of the PICOT question. Each of the keywords from the PICOT question should be used to begin the search. Use the resources provided below to help you search for evidence. 

Search for the Best Evidence

Arrow pointing upSystematic reviews or meta-analyses are regarded as the strongest level of evidence on which to base treatment decisions, however, there are different levels of evidence for each kind of PICOT question.

Refer to the PICOT page on this guide for more information.

  • Level I: Evidence from a systematic review or meta-analysis of all relevant Randomized Controlled Trials (RCTs)
  • Level II: Evidence obtained from well-designed RCTs
  • Level III: Evidence obtained from well-designed controlled trials without randomization
  • Level IV: Evidence from well-designed case-control and cohort studies
  • Level V: Evidence from systematic reviews of descriptive and qualitative studies
  • Level VI: Evidence from single descriptive or qualitative studies
  • Level VII: Evidence from the opinion of authorities and/or reports of expert committees

As you move down this list, the study designs are less rigorous and allow for more bias or systematic error that may distract you from the truth. 


  1. Meta-Analysis is a statistical technique for combining the findings from independent studies to assess the clinical effectiveness of healthcare interventions.
  2. Systematic Review is a comprehensive, unbiased review of multiple research studies that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that research question.
  3. Random Control Trial (RCT) is an experiment that delivers an intervention or treatment; subjects are randomly assigned to control and experimental groups, so it is the strongest design to support cause and effect relationships.
  4. Cohort Study looks at groups of patients who are already taking a particular treatment or have an exposure; subjects are followed over time, and then outcomes are compared with a similar group that has not been affected by the treatment or exposure being studied. 
  5. A Case Control Study looks at patients who already have a specific condition compared to people who do not have the condition. These studies rely on medical records and patient recall for data collection. 
  6. Case Series and Case Reports consist of collections of reports on the treatment of individual patients or a report on a single patient. 
  7. Literature Review is a scholarly analysis of a body of research about a specific issue or topic.

Adapted from Duke Library's EBP Tutorial: Introduction to Evidence-Based Practice

Your textbook covers the different clinical case studies used in evaluating and informing evidence-based practice. While not exhaustive, the most common case studies are: 

  • Systematic Review & Meta-Analysis
  • Randomized Controlled Studies or Trials
  • Case Series / Case Reports
  • Cohort Studies
  • Double Blind

Review the following PowerPoint for an overview of each case study in a nutshell:

 Where you look for information is determined by what kind of question you are asking.  One way of classifying your question is to ask whether you are seeking background information or foreground information.

 Background information is sought when a learner has general clinical questions regarding a topic such as what is the disorder; what causes it; how does it present; what are some treatment options.  These questions can be answered by using "background" resources such as textbooks (both in print and electronic) and narrative reviews in journals which give a general overview of the topic. 

Foreground information answers specific questions a clinician has regarding a specific patient.  Foreground resources can be divided into primary sources such as original research articles published in journals; and secondary sources such as systematic reviews of the topic, and synopses and reviews of individual studies.

Your Librarian Recommends

Robb, M., & Shellenbarger, T. (2011). Strategies for searching and managing evidence-based practice resources. Journal Of Continuing Education In Nursing, 42(7), 461-466 6p. doi:10.3928/00220124-20140916-01

This article provides suggestions for strategies to aid in identifying search terms. Strategies also are recommended for refining searches by using controlled vocabulary, truncation, Boolean operators, PICOT (Population/Patient Problem, Intervention, Comparison, Outcome, Time) searching, and search limits.