One of the areas of difference between quantitative and qualitative research is in the use of and the importance given to the concepts of validity and reliability. The debate centres on whether or not, given the framework of qualitative research, these concepts can or even should be applied in qualitative research. As you know, validity in the broader sense refers to the ability of a research instrument to demonstrate that it is finding out what you designed it to and reliability refers to consistency in its findings when used repeatedly. In qualitative research, as answers to research questions are explored through multiple methods and procedures which are both flexible and evolving, to ensure standardisation of research tools as well as the processes becomes difficult. As a newcomer to research you may wonder how these concepts can be applied in qualitative research when it does not use standardised and structured methods and procedures which are the bases of testing validity and reliability as defined in quantitative research. You may ask how you can ascertain the ability of an instrument to measure what it is expected to and how consistent it is when the data collection questions are neither fixed nor structured.
However, there are some attempts to define and establish validity and reliability in qualitative research. In a chapter entitled ‘Competing paradigms in qualitative research’ (pp. 105—117) in the Handbook of Qualitative Research, edited by Denzin and Lincoln (1994), Guba and Lincoln have suggested a framework of four criteria as a part of the constructivism paradigm paralleling ‘validity’ and ‘reliability’ in quantitative research. According to them, there are two sets of criteria ‘for judging the goodness or quality of an inquiry in constructivism paradigm’ (1994: 114). These are: ‘trustworthiness’ and ‘authenticity’.According to Guba and Lincoln, trustworthiness in a qualitative study is determined by four indicators — credibility, transferability, dependability and confirmability — and it is these four indicators that reflect validity and reliability in qualitative research. ‘The trustworthiness criteria of credibility (paralleling internal validity), transferability (paralleling external validity), dependability (paralleling reliability), and confirmability (paralleling objectivity)’, according to Guba and Lincoln (1994: 114) closely relates to the concepts of validity and reliability.
Trochim and Donnelly (2007) compare the criteria proposed by Guba and Lincoln in the following table with validity and reliability as defined in quantitative research:
- Credibility – According to Trochim and Donnelly (2007: 149), ‘credibility involves establishing that the results of qualitative research are credible or believable from the perspective of the participant in the research’. As qualitative research studies explore perceptions, experiences, feelings and beliefs of the people, it is believed that the respondents are the best judge to determine whether or not the research findings have been able to reflect their opinions and feelings accurately. Hence, credibility, which is synonymous to validity in quantitative research, is judged by the extent of respondent concordance whereby you take your findings to those who participated in your research for confirmation, congruence, validation and approval. The higher the outcome of these, the higher the validity of the study.
- Transferability – This ‘refers to the degree to which the results of qualitative research can be generalized or transferred to other contexts or settings’ (2007: 149). Though it is very difficult to establish transferability primarily because of the approach you adopt in qualitative research, to some extent this can be achieved if you extensively and thoroughly describe the process you adopted for others to follow and replicate.
- Dependability – In the framework suggested by Guba and Lincoln this is very similar to the concept of reliability in quantitative research: ‘It is concerned with whether we would obtain the same results if we could observe the same thing twice’ (Trochim and Donnelly 2007: 149). Again, as qualitative research advocates flexibility and freedom, it may be difficult to establish unless you keep an extensive and detailed record of the process for others to replicate to ascertain the level of dependability.
- Confirmability – This ‘refers to the degree to which the results could be confirmed or corroborated by others’ (2007: 149). Confirmability is also similar to reliability in quantitative research. It is only possible if both researchers follow the process in an identical manner for the results to be compared.
To the author’s mind, to some extent, it is possible to establish the ‘validity’ and ‘reliability’ of the findings in qualitative research in the form of the model suggested by Guba and Lincoln, but its success is mostly dependent upon the identical replication of the process and methods for data collection which may not be easy to achieve in qualitative research.
Source: Kumar Ranjit (2012), Research methodology: a step-by-step guide for beginners, SAGE Publications Ltd; Third edition.