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Public Health Research Guide: Primary Data Sources

Primary Data Sources

A primary source provides direct or firsthand evidence about an event, object, person, or work of art. Primary sources provide the original materials on which other research is based and enable students and other researchers to get as close as possible to what actually happened during a particular event or time period. Published materials can be viewed as primary resources if they come from the time period that is being discussed, and were written or produced by someone with firsthand experience of the event. Often primary sources reflect the individual viewpoint of a participant or observer. Primary sources can be written or non-written (sound, pictures, artifacts, etc.). In scientific research, primary sources present original thinking, report on discoveries, or share new information.

Examples of primary sources:

  • Autobiographies and memoirs
  • Diaries, personal letters, and correspondence
  • Interviews, surveys, and fieldwork
  • Internet communications on email, blogs, listservs, and newsgroups
  • Photographs, drawings, and posters
  • Works of art and literature
  • Books, magazine and newspaper articles and ads published at the time
  • Public opinion polls
  • Speeches and oral histories
  • Original documents (birth certificates, property deeds, trial transcripts)
  • Research data, such as census statistics
  • Official and unofficial records of organizations and government agencies
  • Artifacts of all kinds, such as tools, coins, clothing, furniture, etc.
  • Audio recordings, DVDs, and video recordings
  • Government documents (reports, bills, proclamations, hearings, etc.)
  • Patents
  • Technical reports
  • Scientific journal articles reporting experimental research results

Common Data Types in Public Health Research

Data Types

Quantitative Data

  • Quantitative data is measurable, often used for comparisons, and involves counting of people, behaviors, conditions, or other discrete events (Wang, 2013).
  • Quantitative data uses numbers to determine the what, who, when, and where of health-related events (Wang, 2013).
  • Examples of quantitative data include: age, weight, temperature, or the number of people suffering from diabetes.

Qualitative Data

  • Qualitative data is a broad category of data that can include almost any non-numerical data.
  • Qualitative data uses words to describe a particular health-related event (Romano).
  • This data can be observed, but not measured.
  • Involves observing people in selected places and listening to discover how they feel and why they might feel that way (Wang, 2013).
  • Examples of qualitative data include: male/female, smoker/non-smoker, or questionnaire response (agree, disagree, neutral).
  • Example of qualitative data from a health care setting includes (Curry, Nembhard, & Bradley, 2009):
    • Measuring organizational change.
    • Measures of clinical leadership in implementing evidence-based guidelines.
    • Patient perceptions of quality of care.

Data Sources

Primary Data Sources

  • Primary data analysis in which the same individual or team of researchers designs, collects, and analyzes the data, for the purpose of answering a research question (Koziol & Arthur, nd).
  • Advantages to Using Primary Data
    • You collect exactly the data elements that you need to answer your research question (Romano).
    • You can test an intervention, such as an experimental drug or an educational program, in the purest way (a double-blind randomized controlled trial (Romano).
    • You control the data collection process, so you can ensure data quality, minimize the number of missing values, and assess the reliability of your instruments (Romano).

Secondary Data Sources

  • Existing data collected for another purposes, that you use to answer your research question (Romano).
  • Advantages of Working with Secondary Data
    • Large samples
    • Can provide population estimates : for example state data can be combined across states to get national estimates (Shaheen, Pan, & Mukherjee).
    • Less expensive to collect than primary data (Romano)
    • It takes less time to collect secondary data (Romano).
    • You may not need to worry about informed consent, human subjects restriction (Romano).
  • Issues in Using Secondary Data
    • Study design and data collection already completed (Koziol & Arthur, nd).
    • Data may not facilitate particular research question o Information regarding study design and data collection procedures may be scarce.
    • Data may potentially lack depth (the greater the breadth the harder it is to measure any one construct in depth) (Koziol & Arthur, nd).
    • Certain fields or departments (e.g., experimental programs) may place less value on secondary data analysis (Koziol & Arthur, nd).
    • Often requires special techniques to analyze statistically the data.


Curry, L. A., Nembhard, I. M., & Bradley, E. H. (2009). Qualitative and Mixed Methods Provide Unique Contributions to Outcomes Research. doi: 10.1161/CIRCULATIONAHA.107.742775

Koziol, N., & Arthur, A. (nd). An Introduction to Secondary Data Analysis CYFS Statistics and Measurement. Romano, P. S. Using secondary data. Department of Medicine and Pediatrics. University of California,.

Shaheen, M., Pan, D., & Mukherjee, S. Secondary data sources for research epidemiological and statistical considerations. Epidemiology and Biostatistics. Charles Drew University of Medicine and Science,

Wang, H. (2013). Data Detective: Finding the Gems of Health Data. Information and Education Services. University of Connecticut Health Center.



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