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Issues of validity and reliability in qualitative research
  1. Helen Noble1,
  2. Joanna Smith2
  1. 1School of Nursing and Midwifery, Queens's University Belfast, Belfast, UK
  2. 2School of Human and Health Sciences, University of Huddersfield, Huddersfield, UK
  1. Correspondence to Dr Helen Noble
    School of Nursing and Midwifery, Queens's University Belfast, Medical Biology Centre, 97 Lisburn Rd, Belfast BT9 7BL, UK; helen.noble{at}

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Evaluating the quality of research is essential if findings are to be utilised in practice and incorporated into care delivery. In a previous article we explored ‘bias’ across research designs and outlined strategies to minimise bias.1 The aim of this article is to further outline rigour, or the integrity in which a study is conducted, and ensure the credibility of findings in relation to qualitative research. Concepts such as reliability, validity and generalisability typically associated with quantitative research and alternative terminology will be compared in relation to their application to qualitative research. In addition, some of the strategies adopted by qualitative researchers to enhance the credibility of their research are outlined.

Are the terms reliability and validity relevant to ensuring credibility in qualitative research?

Assessing the reliability of study findings requires researchers and health professionals to make judgements about the ‘soundness’ of the research in relation to the application and appropriateness of the methods undertaken and the integrity of the final conclusions. Qualitative research is frequently criticised for lacking scientific rigour with poor justification of the methods adopted, lack of transparency in the analytical procedures and the findings being merely a collection of personal opinions subject to researcher bias.2 ,3 For the novice researcher, demonstrating rigour when undertaking qualitative research is challenging because there is no of accepted consensus about the standards by which such research should be judged.2

Although the tests and measures used to establish the validity and reliability of quantitative research cannot be applied to qualitative research, there are ongoing debates about whether terms such as validity, reliability and generalisability are appropriate to evaluate qualitative research.2–4 In the broadest context these terms are applicable, with validity referring to the integrity and application of the methods undertaken and the precision in which the findings accurately reflect the data, while reliability describes consistency within the employed analytical procedures.4 However, if qualitative methods are inherently different from quantitative methods in terms of philosophical positions and purpose, then alterative frameworks for establishing rigour are appropriate.3 Lincoln and Guba5 offer alternative criteria for demonstrating rigour within qualitative research namely truth value, consistency and neutrality and applicability. Table 1 outlines the differences in terminology and criteria used to evaluate qualitative research.

Table 1

Terminology and criteria used to evaluate the credibility of research findings

What strategies can qualitative researchers adopt to ensure the credibility of the study findings?

Unlike quantitative researchers, who apply statistical methods for establishing validity and reliability of research findings, qualitative researchers aim to design and incorporate methodological strategies to ensure the ‘trustworthiness’ of the findings. Such strategies include:

  1. Accounting for personal biases which may have influenced findings;6

  2. Acknowledging biases in sampling and ongoing critical reflection of methods to ensure sufficient depth and relevance of data collection and analysis;3

  3. Meticulous record keeping, demonstrating a clear decision trail and ensuring interpretations of data are consistent and transparent;3 ,4

  4. Establishing a comparison case/seeking out similarities and differences across accounts to ensure different perspectives are represented;6 ,7

  5. Including rich and thick verbatim descriptions of participants’ accounts to support findings;7

  6. Demonstrating clarity in terms of thought processes during data analysis and subsequent interpretations3;

  7. Engaging with other researchers to reduce research bias;3

  8. Respondent validation: includes inviting participants to comment on the interview transcript and whether the final themes and concepts created adequately reflect the phenomena being investigated;4

  9. Data triangulation,3 ,4 whereby different methods and perspectives help produce a more comprehensive set of findings.8 ,9

Table 2 provides some specific examples of how some of these strategies were utilised to ensure rigour in a study that explored the impact of being a family carer to patients with stage 5 chronic kidney disease managed without dialysis.10

Table 2

Strategies for enhancing the credibility of qualitative research

In summary, it is imperative that all qualitative researchers incorporate strategies to enhance the credibility of a study during research design and implementation. Although there is no universally accepted terminology and criteria used to evaluate qualitative research, we have briefly outlined some of the strategies that can enhance the credibility of study findings.