Research: Qualitative or quantitative?

Last updated: Friday, June 16, 2017

An early issue to decide is whether your research question would best be answered using a broadly qualitative or quantitative approach. This is an important distinction to make, as it will determine the whole design of your study: from your initial literature review right the way through to your data analysis. In case you're not entirely sure of the difference:

  • Quantitative research is concerned with trying to measure something. It delivers results as numbers, so it asks questions such as ‘how long?’ or ‘how many?’, and is the approach with which pharmacists are most familiar.
  • Qualitative research attempts to establish how people interpret their experiences and the world around them; it asks ‘what does it feel like?’ or ‘what do you think about x?’. It often aims to gather data in as natural a setting as possible (e.g. in a participant's workplace). 

Quantitative research tends to collect data through questionnaires, surveys, validated scoring systems (e.g. the Hospital Anxiety & Depression Scale), or a series of measures (e.g. blood pressure). In contrast, qualitative researchers use techniques such as direct observation, interviews, and focus groups.

There are differences when it comes to data analysis too. Quantitative research generally involves the use of statistics to summarise the data generated, and to make inferences from it. This analysis can be done quite speedily with a computer program. The analysis of qualitative research is more time-consuming since the data often take the form of transcripts of interviews or focus groups, or field notes from observing a particular interaction. Researchers may look for themes within the data, describe an experience in detail, or develop a theory about why people behaved in the way they did.

Recruitment can also differ. You usually need more participants in a quantitative study to make sure that any differences seen are statistically significant, and you may have to be quite selective ('purposeful sampling') to make sure that the people you're studying are suitable – e.g. elderly patients and pregnant women are often excluded from clinical trials. In qualitative research, smaller numbers are acceptable and recruitment is typically more random.

Finally, although either of these approaches can be used by itself, they are often combined. For example, qualitative research can be used to gather preliminary data to inform the design of a quantitative project. Alternatively, a qualitative study conducted after completing a quantitative one can help to explain the numbers: why did 75% of people prefer x and not y? A particularly common combination is to conduct a survey (quantitative) followed by a focus group (qualitative).