Validity and reliability

Reliability and validity are generally mentioned together, due to the fact that they are related in terms of research accuracy and credibility. Reliability relates to the degree of consistency of data collected on several occasions or by different observers (Creswell, 2003;). On the other hand, validity is used to consider whether the findings will accurately represent the social phenomena being studied (Creswell and Miller, 2000). As stated in Berry (2002), validity is defined as the extent to which the measuring instrument is appropriate to the task, whereas reliability relates to how the results of repeated tests are consistent with the selected measuring instrument. Silverman (2010) demonstrates how the qualitative approach can incorporate measures dealing with validity and reliability. In this study, there are multiple methods used to establish the validity and reliability of the findings.

Triangulation is a method used by the qualitative researcher to establish and ensure the validity of a study by means of analysing a research question from multiple perspectives and evaluating these findings (Golafshani, 2003; Guion et al., 2011). Guion et al. (2011) also presents five types of triangulation that can be applied: data triangulation, investigator triangulation, theory triangulation, methodological triangulation, and environmental triangulation. Patton (2002) states that “triangulation strengthens a study by combining methods. This can mean using several kinds of methods or data, including using both quantitative and qualitative approaches” (p. 247). Nevertheless, Barbour & Kitzinger (1998) argues that mixing paradigms may be possible; however, mixing methods within one paradigm might be problematic. Therefore, the researcher needs to consider that each method within the qualitative research paradigm has its own assumptions in terms of its theoretical framework to bring to the research.

In this study, data triangulation is used to test the validity of the data. Data triangulation uses different sources of information in order to assess the validity of a study. In this study, Thai EFL teachers and students at upper secondary level from various state schools in Bangkok have in-depth interviews and focus group interviews conducted on them respectively. Both sets of interviews are carried out to gain insights into participants’ perceptions of English language education in Thailand. During the data analysis stage, the findings from Thai EFL teachers and learners would be compared to determine the similarities and differences they display in the topic. Thurmond (2001, p. 254) notes that among the distinctive advantages of triangulation are that it results in “increasing confidence in research data, creating innovative ways of understanding a phenomenon, revealing unique findings, challenging or integrating theories, and providing a clearer understanding of the problem”. It may be seen that the benefits lie

largely in the quantity and diversity of data used for analysis. However, there are also limitations in applying triangulation to a study. The amount of time to be expended is regarded as one of the weaknesses of triangulation. This is because greater planning and organisation are required to collect more data. Moreover, there may be possible disagreements based on researchers’ biases, contradictions due to the theoretical frameworks used as well as little understanding about why a triangulation strategy is being applied in a study (Thurmond, 2001). In-depth interviews and focus group interviews would be recorded in this research; thus, the researcher must be aware of the accuracy of the interpretation of the transcripts. Accordingly, in order to establish reliability and validity within my research, raw data will be checked with the interviewees in order to reduce potential misunderstandings where questions and answers are concerned. As such, the findings will be judged on whether the data have been accurately interpreted in order to make sure that no distortion has occurred. Likewise, providing quotes from interviewees throughout the study can increase the credibility of the information. However, the researcher must be aware of the issue of not identifying the participant’s quotes so that they can easily be traced back to an individual, especially if confidentiality has been promised.

Furthermore, the literature review can also assist the researcher in establishing the theoretical validity of their findings. The findings will also be confirmed by comparing them with the literature review, which will summarise previous related research. Shenton (2004) points out that the examination of previous research findings is done to assess the degree to which the findings’ results are congruent with those of previous studies. Silverman (2010) also claims that the ability of the researcher to relate findings to an existing knowledge base is a key criterion for evaluating their credibility.

In addition, Patton (2002) points out that the credibility of the researcher is crucial in qualitative research, since the researcher is the major instrument of data collection and analysis. Thus, having a similar background, qualifications and experience is considered to be highly beneficial in ensuring the credibility of the research. Thus, as a former English language teacher at upper secondary level in Bangkok, this researcher can also check the validity of findings where other teachers have been interviewed, owing to the fact that the researcher has partaken in a similar education system and curriculum.