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Nursing & Health Resources at Hostos Library: Understanding research

Library resources for LPN and RN students

Evidence pyramid

The EVIDENCE PYRAMID is often used to illustrate the development of evidence. At the base of the pyramid is animal research and laboratory studies - this is where ideas are first developed.

(Source:, Definitions from CEBM)

As you progress up the pyramid the amount of information available decreases in volume, but increases in relevance to the clinical setting.


Meta Analysis - systematic review that uses quantitative methods to synthesize and summarize the results.

Systematic Review - summary of the medical literature that uses explicit methods to perform a comprehensive literature search and critical appraisal of individual studies and that uses appropriate statistical techniques to combine these valid studies.

Randomised Controlled Trial - Participants are randomly allocated into an experimental group or a control group and followed over time for the variables/outcomes of interest.

Cohort Study - Involves identification of two groups (cohorts) of patients, one which received the exposure of interest, and one which did not, and following these cohorts forward for the outcome of interest.

Case Control Study - study which involves identifying patients who have the outcome of interest (cases) and patients without the same outcome (controls), and looking back to see if they had the exposure of interest.

Case Series - report on a series of patients with an outcome of interest. No control group is involved.

(Source:, Definitions from CEBM)

Structure of a Research Paper

Scientific articles in the health sciences tend to be structured similarly, in the IMRAD format.  IMRAD is an acronym that stands for:

I = Introduction & Importance : the authors make a case for the research. What do we know about the subject and why is this research important?

M = Methods: the authors explain how they conducted their research

R = Results: the authors describe their findings and the outcomes of the research


D = Discussion: the authors discuss findings, explain how it relates to other research, discuss limitations of the study and directions for future research.

General resources for understanding research


PICO helps you formulate a targeted research question. 

P=Problem or Patient

I=Intervention or Indicator




PICO questions can fall into the following categories:






Frequency or rate