Empirical studies are original research papers that use data derived from direct observation, interviews, or experimental methods (also called primary research or scholarly articles). Empirical studies and their results are published in peer-reviewed academic journals.
Quantitative research measures variables using a numerical system, analyzes these measurements using statistical models, and reports on relationships and associations among the studied variables (example: PMID 36214599).
Qualitative research uses non-numeric information to explore individual or group characteristics, producing findings not arrived at by statistical procedures or other quantitative means, such as observations of behavior or personal accounts of experiences. Techniques may include content analyses of narratives, in-depth interviews, focus groups, participant observation, and case studies (example: PMID 33601922).
MIxed methods studies combine quantitative and qualitative elements of data collection (example: PMID 36821362).
Articles that report empirical research usually contain different sections which relate to the steps of the scientific method.
Abstract - The abstract provides a statement on the background or purpose (what was being studied and why) and a brief summary of the research.
Introduction - The introduction sets the research in a context, providing a review of established and related research and develops the hypotheses for the research.
Methods - The methods section describes how the research was conducted - the experimental group or sample, control, variables, number of test subjects, test conditions, etc.
Results - The results section describes the outcomes of the study in numeric form as tables, charts, or graphs, etc., often with statistical analysis.
Discussion (or Conclusion or Significance) - The discussion section contains the interpretations and implications of the study.
Works Cited (or References or Bibliography) - This section lists the articles, books, and other material cited in the paper.
Primary
What is it? Original research, based on observation/experience/investigation.
Examples: Results of studies (such as Randomized Controlled Trials, Qualitative Studies) with methodologies, data, results, and conclusions.
Where to find it: Published in peer-reviewed journals such as NEJM, Critical Care Nurse, JAMA, Journal of Advanced Nursing (found in databases like PubMed & Embase). Dissertations, conference abstracts or proceedings.
Secondary
What is it? Secondary articles summarize and appraise multiple relevant primary studies to answer a clinical question. Also called filtered, pre-appraised, or synthesized, or evidence summaries.
Examples: Review articles, systematic reviews, meta-analysis, Best Practice Guidelines.
Where to find it: Cochrane Library, TRIP database. Filters in databases like PubMed, Embase for systematic reviews/meta-analyses in databases. Scholarly books (monographs).
Tertiary
What is it? An overview of primary and secondary sources such as textbooks or handbooks. A background/introduction to principles and practices within the discipline.
Examples: “Harrison's Principles of Internal Medicine.” “Watson's Clinical Nursing & Related Sciences.”
Where to find it: Textbooks, review articles.
"Gray"
What is it? Literature not readily available through conventional academic sources, also known as ‘hard to find.’ Usually not indexed or published in a peer-reviewed journal.
Examples: Proceedings from the 25th Conference on Retroviruses & Opportunistic Infections. American Nurses Association Healthy Nurse, Healthy Nation Year Four Highlights 2020-2021.
Where to find it: Internet searches, assocations/societies, data sets, conference proceedings, clinical trial data, government reports, trade journals, statistics.
Case Report
What is it? A case report is a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient.
Examples: Winston LA, Fischer MP. A 24-Year-Old Woman Presenting With Altered Mental Status and Multiorgan Failure. Chest. 2021 Sep;160(3):e279-e283. doi: 10.1016/j.chest.2021.04.071. PMID: 34488968; PMCID: PMC8413725.
Where to find it: Published in peer-reviewed clinical journals which are found in databases like PubMed & Embase.