How to decide between qualitative and quantitative research
Before getting to grips with qualitative versus quantitative research, there are a few basic ideas that need to be understood. So do read the next few sections carefully.
Research should be about discovering 'truth' - but what exactly is 'truth'? It often depends on how one looks at things - see the following box.
Common idioms which illustrate how there are (at least) two sides to most viewpoints
It is therefore important as a researcher to understand how you are looking at your research and to be able to explain this to others who need to know about your research. The terminology for doing so is in terms of what are called 'research paradigms' or 'research frameworks'.
Research paradigms and frameworks
Quite generally a way of looking at the world is known as a 'paradigm'. A 'research paradigm' is a 'school of thought' or 'a framework for thinking' about how research ought to be conducted to ascertain truth. Different writers tend use different terminologies when discussing research paradigms, because of where they are coming from. For practical purposes, though, various research paradigms can normally be simplified into just two:
- The 'traditional' research paradigm which is essentially quantitative.
- The 'interpretivist' research paradigm which is essentially qualitative. (The term is due to Denzin and Lincoln (1994), Handbook of Qualitative Research. Beverly Hills, CA: Sage. p. 536.).
This distinction will serve for starters but be aware that there are any number of different research paradigms in the literature and that there is no agreement among academics on how many there are or the finer distinctions between them.
Research in the traditional research paradigm is essentially quantitative. It relies on numerical data and mathematical or statistical treatment of that data. The 'truth' that is uncovered is thus grounded in mathematical logic.
The traditional research paradigm lends itself to highly valid and highly reliable research. So why do researchers ever use anything else? The reason is that the traditional research paradigm can only be used where the variables that affect the work can be identified, isolated and relatively precisely measured – and possibly, but not necessarily, also manipulated. This is how research in the natural sciences normally operates.
Alternative terms for the traditional research paradigm
Researchers who can work in the traditional research paradigm are fortunate because high reliability and validity are held in great esteem. The proponents of the paradigm tend to take its advantages for granted, and theses grounded in it generally take the high reliability and validity as self-evident.
Limitations of quantitative research
Quantitative research and living beings
Quantitative research is not normally appropriate where living beings are concerned.
Living beings are affected by numerous interacting variables, such as tiredness, hunger, stress, etc and these variables cannot normally be isolated from one another or measured, and it is certainly impossible, let alone normally unethical, to hold some constant while manipulating others.
This said, the traditional research paradigm with its quantitative approach can still lend itself to research touched by human and other animate behaviour if the data is numerical and if the sample is sufficiently large for the effects of individual vagaries effectively to cancel one another out. One example could be the performance of school leavers in national examinations across a country over a period of years. Another could be an investigation into the yields of a hybrid crop using large fields of control and experimental plants.
Quantitative research and the types of questions it can and cannot answer
Research set in the traditional research paradigm can answer questions about what is happening and the statistical chances of something happening in the future, but - and this is a big 'but' - it cannot directly answer questions about why something is happening or may happen, nor about the existence of anything else that may be relevant - although answers to such questions may be provided by an established theory within which the research fits.
So the traditional research paradigm is generally not appropriate for research involving small samples of living beings. Then, the variables which stem from individual vagaries and subjectivity do not cancel one another out; neither can variables be readily identified or measured, let alone isolated and held constant while others are varied. Even with a large sample, there are sometimes ethical or pragmatic reasons why variables cannot be held constant or manipulated experimentally.
Alternative terms for the interpretivist research paradigm
So a different approach is needed and the research has to be set in the interpretivist research paradigm.
What this involves is more like in-depth investigations to establish a verdict in a court of law than experiments in a laboratory. The evidence can be circumstantial and even where there are eye-witness accounts, doubt can always be cast on the veracity or reliability of the observers. A verdict must be reached on what is reasonable, i.e. the weight of evidence one way or the other and on the power of the argument. Data gathered within the interpretivist research paradigm is primarily descriptive, although it may be quantitative, as for example in sizes of living areas, coded questionnaires or documentary analysis. The emphasis is on exploration and insight rather than experiment and the mathematical treatment of data.
Qualitative research and the types of questions it can answer
Qualitative research in the interpretivist research paradigm can address questions about how and why something is happening. It can also address questions about what is happening in a wider context and what is likely to happen in the future - but it can seldom do so with statistical confidence, because the 'truth' is not grounded in mathematical logic. The 'truth' has to be a conclusion in the mind of a reader (or listener), based on the researcher's power of argument. So different recipients of the research may come to understand different 'truths', just as jurists in a court of law may disagree. It is therefore important for those who use the interpretivist research paradigm to present their work as convincingly as possible. If you are working in this paradigm, your supervisor(s)* will advise you further.
Which research paradigm for your research?
Your research topic will normally decide your research paradigm, but do bear in mind that different parts of a substantial research project may well sit comfortably in different research paradigms. If so, it is important to be able to explain where and how this is so.
Also, bear in mind that students who use the interpretivist research paradigm normally have to do a considerable amount of justification. In contrast, those who use the traditional research paradigm often never even mention it.
I have found it important for researchers, irrespective of their topic and chosen research paradigm, to understand the advantages and limitations of both paradigms. Not only does this lead to less heated inter-group discussions, it also eases the way for interdisciplinary research - and many significant advances come from interdisciplinary research.