Primary vs Secondary Data

Data can be quantitative or qualitative, primary or secondary.

Primary data are gathered first hand from source, directly by the researcher(s).For example, Milgram (1963) collected primary data when he studied obedience in a laboratory, and Bandura et al. (1961) collected primary data when they looked at children copying role models. Psychological studies usually gather primary data. Questionnaires, observations, content analyses and experiments are all ways to gather primary data.

Secondary data have already been gathered by someone and are used by someone else for further research. For example, government statistics from a census can inform researchers about the number of females living alone. A meta-analysis, in which researchers pool data on a particular topic, uses secondary data because the data studied are not gathered first hand.

Evaluating the use of primary and secondary data in research

Primary and secondary data can be compared in terms of cost (one is relatively more expensive than the other), validity (one is more valid, perhaps) and strength of the conclusions (one is more trust-worthy and credible). Primary data may be more recently gathered than secondary data.

Relative cost

Primary data are expensive to obtain because each researcher or research team has to start from the beginning of a study and follow the whole study through, including finding participants, organising materials and running the study. Secondary data are cheaper because they already exist.


Primary data are gathered first hand, following careful operationalisation of variables and using carefully chosen procedures. Consideration is given to what is being gathered in terms of data so that they are about ‘real life’. Operationalising the IV (the variable being manipulated) is done so that it represents what is to be measured in general, therefore primary data should be valid because the study is designed and carried out for the main purpose of the research.

Secondary data, on the other hand, are likely to have been gathered for some other purpose or for an unclear purpose. Often secondary data have already been analysed, which can bring in an element of subjectivity. If secondary data gathered for one purpose are used for another they may not be valid for the second purpose.


Primary data might be considered to be more trustworthy, in that they have greater validity than secondary data. If they are collected objectively, with careful planning and sampling, controls in place and other features of methodology adhered to, then they are likely to be scientifically gathered for the stated aim of the study. This means that they are more credible. If, however, data gathered for one purpose are used for a different purpose or aim, then this use of secondary data might lack credibility.

Time period

Primary data are likely to be gathered at the time of the study and conclusions will be drawn then.

Secondary data, however, might have been gathered some time ago. Conclusions drawn from these data might not be valid, as cultures, for example, change over time, as do people

Can you answer the following?

See if you can answer these questions:

  1. Explain why research which is carried out first-hand gains credibility.
  2. Give one example of psychological research that produced primary data and explain why it was primary data.
  3. Give one reason why a psychologist may choose to use secondary data.
  4. When does primary data become secondary data?
  5. Give two examples of research methods used in psychology which use secondary data.
  6. Provide one example of psychological research that used secondary data and explain why it is secondary data.
  7. Which type of data is considered to be less time consuming and costly?
  8. Which type of data is likely to be considered more up –to-date?