Module Components

• Learning Activity

Topics

• Hierarchy of Evidence
• Primary Sources of Evidence
• Secondary Sources Evidence
• Evidence Appraisal

NRSG 790-Methods for Research and Evidence-Based Practice

Module 5: Overview: Critically Appraising Evidence

Primary Sources of Evidence

In healthcare literature, a primary source is a document or record, usually a peer reviewed journal article, which reports a study, experiment, event or other phenomenon firsthand. Primary sources detail original research and are usually written by the person(s) who did the research or conducted the study.

• Reading the methods section of a study will help to determine what kind of research was conducted
• Primary sources of evidence are most accessible through Bibliographic Databases such as CINAHL, PubMed, MEDLINE, etc

Randomized Controlled Trials are studies in which subjects are randomly assigned to two or more groups; one group receives a particular treatment while the other receives an alternative treatment (or placebo). In a double blinded study, patients and investigators are "blinded", that is, they do not know which patient has received which treatment. This design feature is a major control to reduce bias.

Cohort Studies are observational studies in which one or more populations are compared, often over time to investigate the course of an exposure. These studies are not randomized and are more subject to bias due to the inability to control for factors that may influence the outcome.

Case Control Studies are observational and study a population of patients with a particular condition and compare it with a population that does not have the condition. It looks at the exposures that those with the condition might have had that those in the other group did not. These studies are more subject to bias due to the inability to control for factors that may influence the outcome.

Cross-Sectional Studies look at diseases and other factors at a particular point in time, instead of longitudinally. These are studies are not relational or causal.

Case Studies are usually single patient cases and are used to identify new issues in healthcare. They are descriptive in nature and subjective by definition, and would not infer relational or causal effect