In qualitative research, trustworthiness features are based on issues of reliability and validity. Reliability refers to the consistency with which something is measured over time and validity refers to the degree to which something measures what it is designed to measure (Merriam, 1998). Qualitative research addresses the issues of reliability and validity in a way that contrasts with a quantitative approach. According to Denzin and Lincoln (1994), qualitative research should assess the credibility, dependability, conformability and transferability of the findings instead of using reliability and validity which are more relevant in quantitative research (see details in section 4.5.2 and 4.5.3 for reliability and validity in quantitative research). Thus, the researcher discussed the credibility of the findings to measure internal validity, applied the term dependability in place of reliability and used transferability with regards to the external validity (Merriam, 1998).
3.4.1 Credibility
The credibility or internal validity of the study suggests the findings of the study should be accurate and credible from the perspective of the researcher, the participant and the reader (Merriam, 1998). This criterion becomes a key component of the research design (Creswell, 2003); Miles & Huberman, 1994). Therefore, the researcher needs to demonstrate the credibility of the findings in order to be accepted by the reader as valid. To maximise the credibility (internal
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validity) of the findings in this study, the researcher employed various strategies (Creswell, 2007), namely, triangulation, member checks, long-term observation and peer validation (Merriam, 1998).
Triangulation. The use of multiple data sources to establish the credibility of the
findings (Merriam, 1998; Creswell, 2007; Yin, 2009) was achieved by using data obtained from survey, interviews, classroom observation and documents. These different methods helped to check consistency between what the participants reported in the survey, said in the interviews, performed during classroom observation and described in their lesson plan. For instance, in order to determine the consistency in pre-service teachers’ feedback on TPACK understanding gathered from the survey method, the researcher employed methods such as interviews, classroom observation and lesson plans to triangulate and further support the evidence from the survey.
Member checks. Participants’ feedback was obtained to validate the accuracy of the
recorded information from the interview transcripts and case stories. This strategy involves returning the transcripts and findings of the study to the participants so that they can reflect on the interpretations that the researcher has made in order to protect against researcher’s bias (Lincoln & Guba, 1985). If the researcher’s interpretation of the meaning of the events has been accepted by the people whose sense-making is under study, the study has achieved interpretive validity (Eisenhart, 2006), in other words, the interpretations of the findings are accurate and credible (Merriam, 1998). In this study, the researcher returned the transcripts and the participants’ case stories to the participants and invited them to give feedback on anything they felt did not accurately reflect what was said. This offered them the opportunity to add further information for some aspects that might appear unclear.
Long-term observation. The researcher gathered data over a period of time with
repeated observations in order to increase the validity of the findings (Merriam, 1998). In this study, at least two classroom observations were carried out with the
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pre-service teachers. Furthermore, most of the interview sessions were conducted during the school period which enabled the researcher to observe the phenomenon and obtain more insights about the context.
Peer validation. The researcher discussed the findings and the interpretation of the
findings with academic colleagues in order to ensure that the interpretations were not based on the researcher’s needs and her own biases. Furthermore, the researcher discussed researcher’s perspective, the data analysis, the coding and the findings with her supervisors so that the interpretations that the researcher made were validated and justified according to the data (Merriam, 1998).
3.4.2 Dependability and Conformability
Reliability in qualitative research is related to the issue of consistency and dependability of the data collected in the study (Lincoln & Guba, 1985). The purpose is to ensure that if a researcher followed the same procedures and conducted the same case study again, the same outcome and conclusion could be achieved (Yin, 2003; Cohen et al., 2000). Reliability in qualitative research involves member checks, long-term observation and triangulation, the same measures used to check the credibility of the findings (Lincoln & Guba, 1985). The data reviewed could also be supported with the research audit trail (Lincoln & Guba, 1985) to make note of the researcher’s thinking and reflection, and reporting of the justification for all decisions made during the research process. Maintaining the audit trail, as well as keeping an ongoing reflection using a researcher’s journal and memos, field notes and transcripts, also offers the reader an opportunity to assess the conformability of the findings.
3.4.3 Transferability
Transferability refers to the extent to which the phenomenon under study can be transferred to another context (Lincon & Guba, 1985). It is possible to test for transferability in this study by comparing its situation to other situations to see the extent that the interpretation might be applicable in such settings, or at least to help readers in understanding other situations (Yin, 1994). The greater the similarity between the cases, the greater is the degree of transferability. Thus, by providing a
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rich, thick description (Merriam, 1998, p. 29) in the report, giving voice to the research participants when reporting findings and describing the findings with enough detail in each case (Creswell, 2007; Lincoln & Guba, 1985), the reader could determine the transferability and external validity of the research outcomes. As suggested by Rubin and Rubin (1995), the researcher outlined in detail the steps taken in the research process, offering the reader a detailed description of the research design, data collection procedure, sampling and data analysis. By being transparent, communicable and coherent, the reader is able to assess what the researcher has done and to apply it to other contexts.