What Are Some of the Differences Between Primary & Secondary Data?

Updated February 21, 2017

Research can be carried out with 2 different types of data; primary and secondary data. What type of data is best is really determined by the research goal. Companies should use both types of information, as secondary data can be used to create a new question, while the primary data can determine the answer to the question.


Primary data is collected firsthand by a researcher. It normally is collected through experiments, surveys, questionnaires, focus groups, interviews and taking measurements. Secondary data has already been collected and is available to the public. The sources of secondary data include books, journals, census data, biographies, articles and databases.


Primary research is tailored specifically for the project and tends to be more accurate. While secondary data can provide plenty of information, it is less accurate because the data collected was not collected specifically for the questions. Primary data is customised while secondary data is not.

Scientific Method

Primary data follows the scientific method. A hypothesis is formed, data is collected from an experiment based on the hypothesis and the hypothesis is proven correct or not. Secondary data does not start with a hypothesis as the data is already collected. Patterns and insights are found within the secondary data and then the observation on that data is made.


The cost of obtaining primary data is typically more than secondary. This cost includes monetary values as well as time. Primary data will include the chemicals needed to perform the experiment, any scientific analysis, and most importantly the time needed to carry out the data collection, determine the results and conclusions and then write up the data for publication. Secondary data is typically available for free or for the subscription fee to the database, magazine or journal. Once the subscription is obtained the data can be obtained immediately so it takes much less time to collect secondary data.

Types of Science

Primary data is used by all branches of science but especially for what is known as the “hard” sciences: chemistry, biology, physics, agriculture and more. The vast majority of papers published in these fields consist of primary data. It is the social sciences where secondary data is used extensively. Social science research will frequently take secondary data to find patterns within the area of study.

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About the Author

Liz Tomas began writing professionally in 2004. Her work has appeared in the "American Journal of Enology and Viticulture," "BMC Genomics" and "PLoS Biology." She holds a Master of Science in food science from Cornell University and a Bachelor of Science in biochemistry from the University of New Hampshire. She is pursuing her Ph.D. in oenology at Lincoln University.