Types of data: Qualitative and Quantitative data; Primary and Secondary data

Qualitative and Quantitative




If you have quantitative data; you need to know whether it is nominal, ordinal or interval/ratio; this handout will help to make sure! levels-of-measurement-1-1 (1)

What is primary data?

Primary data is collected first hand by the researcher for a specific research purpose. The researcher might collect information via observation, psychometric test, interview etc and this data may be qualitative or quantitative.  With quantitative primary data, the researcher might analyse the data using descriptive and inferential statistics or with qualitative primary data they might conduct a grounded theory or discourse analysis.
An example of a qualitative primary data collection from clinical psychology would be when Brown et al (1986) interviewed participants and information was collected about self esteem, life events and perceived social support over the course of the longitudinal study.
An example of quantitative primary data collection was encountered in Castner et al (1998) study of the rhesus monkeys exposed whilst still ‘in utero’ to radiation to see whether this led to symptoms of schizophrenia later in life; here the monkeys were observed for signs of hallucinations (a nominal scoring system would be used such a tally chart).
The monkeys were also given cognitive tests to see whether exposure to radiation led to disordered thinking. These tests would have led to ratio data in the form of scores on standardised psychological tests and this is also a form of primary data collection.
Primary data contrasts with secondary data which is collected indirectly via existing records about people who fit the criteria for the target population or it can be previously published research in a certain area, which is sued for example to inform the literature search that a psychologist performs before embarking on a new piece of research; here you can see that the researcher never actually collects any data themselves as in primary research.

What is secondary data?

When a researchers uses secondary data, this means that someone else has already collected the information, for a different purpose and the information has been stored on record for use by other researchers. The researcher will re-analyse this second hand data for a new purpose.
Results of psychological studies are classed as secondary data and often a researcher will conduct an in-depth review of the secondary data in the area of interest before embarking upon his or her own primary data collection.
In clinical psychology, secondary data might include medical records made by doctors including diagnoses of disorders or how a patient has responded to treatments options. It could also include school reports which provide insight into an individual’s life before the onset of a disorder.
A specific example of the use of secondary data in clinical psychology was Gottesman and Shields as an example of a twin study where pre-existing diagnoses of schizophrenia and other psychiatric disorders had already been made in their twin pairs whose information was gathered from records held by Bethlem and Maudsley hospital.

Revision Activity

Write the examples into the correct section of the grid. If possible write in brackets the level of measurement of any quantitative data. You may wish to continue adding further examples as you revise this unit.
  • Diagnosis given by duty psychiatrists in Rosenhan (1973)
  • Information gathered in interviews in Vallentine et al
  • Case histories and medical notes in the twin pairs in Gottesman and Shields (1966)
  • Personality tests and analysis of tape recorded speech from semi-structured interviews with the twin pairs in Gottesman and Shields (1966)
  • Diagnoses on admission and release in Pontizovsky et al’s (2006) study of reliability of diagnoses
  • Information from standardised interviews with 1555 18-25 year old German women about what prescription drugs they were on and also used to diagnose mental disorders (Hach el al, 2004)
  • Information provided by the doctors of the 1555 18-25 year old German women about diagnosis and prescriptions (Hach el al, 2004)

Learning Objective: Evaluate the use of primary and secondary data

You need to be able to present two strengths and two weaknesses of both primary and secondary data. You should also be able to present a more elaborated evaluation meaning that you may in fact wish to keep revision notes on more than two strengths and weaknesses and link these to specific examples from research studies. 

Practice comparing primary and secondary data

Similarity 1: Both primary and secondary data could be seen as reliable as
Similarity 2: Both primary and secondary data could be seen as valid as..
Difference 1: The collection of primary data may be more expensive then secondary data because…
Difference 2: Primary data could be considered more valid then secondary data because…
Difference 3: Secondary data may be less reliable then primary data because…
Difference 4: Secondary data may be more practical and lead to more credible findings particularly if…’
Difference 5: Primary data may be considered more credible then secondary data because….

Practice Questions
1. Give two strengths and two weaknesses of primary data (2+2)
2. Give two strengths and two weaknesses of secondary data (2+2)
3. Evaluate the use of primary data in clinical psychology (6)
4. Evaluate the use of secondary data in clinical psychology (6)
5. Compare the use of primary and secondary data in clinical psychology (8)
6. Researchers in clinical psychology often use hospital records as part of their data collection. They may also collect data directly from their participants. Explain why different types of data are used and evaluate the use of these different types of data. (6)