Puertos y elementos multipuerto Ecuaciones constitutivas

4.9.1 Reliability

The concepts of reliability and validity are important to both the quantitative and qualitative studies (Golafshani, 2003). Nunnally (1967: 206) cited in Cortina (1993:98) defined reliability as "…the extent to which [measurements] are repeatable and that any random influence which tends to make measurements different from occasion to occasion is a source of measurement error". This does not refer to how reliable the

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subjects (people being interviewed) are, but the extent to which they are in agreement with the scores being used and their responses stay the same over time (Bolarinwa, 2015), which in the case of this study is the scores of the items used to measure resilience. The three major forms of assessing reliability are internal consistency reliability, test-retest reliability, and alternate form reliability.

4.9.2 Internal consistency reliability

Internal consistency refers to “…the extent to which items on the test or instrument are measuring the same thing” (Bolarinwa, 2015:199). In the case of this study, items are the 24 items on which resilience is measured. The advantage of internal consistency reliability is that it does not rely on time period as it is estimated after only one test administration. This uses the so-called “split-half” reliability index and coefficient alpha index on all possible split halves of the sample and taking the average of these. It is commonly measured using Cronbach alpha (). The higher the value of alpha, the higher the reliability of the measure. As a general convention, researchers should strive for reliability values of 0.70 and higher (Nunnally & Bernstein, 1994 cited in Bolarinwa, 2015:199)

In this research, reliability of resilience was measured using internal consistency

reliability. An internal consistency (Cronbach’s alpha) of 0.854194 was observed,

indicating a good measure of reliability. This value of Cronbach’s alpha compares well with the Cronbach’s alpha of 0.82 observed by Mampane (2012) and 0.82 observed by Mampane & Bouwer (2011).

4.9.3 Test-retest reliability (or stability)

Test-retest reliability refers to reliability or stability is obtained using similar scores over time with the same group of respondents. This is done by administering the same or similar questionnaire to the same or similar to the same individuals under similar conditions. Correlation of test scores at different time periods is used to assess the reliability of the questionnaire.

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4.9.4 Alternate form reliability

As the name suggests, alternate form reliability refers to administering a questionnaire and its alternate form at the same point in time to the same group or different group of individuals by changing the wording. The higher the correlation between the two forms, the more equivalent they are. Alternate form reliability is similar to the Test-Retest reliability except in the case of Alternative form an alternative test is given (Yang & Miller, 2008).

4.9.5 Choice of reliability measure

In this study, internal consistency reliability will be used to test the reliability of resilience measured using the Cronbach alpha measure. The reason for this is that this study is not a longitudinal study but looks at school violence at the particular time when the study was undertaken. The second reason is that the study is not about testing reliability of the R-MATS questionnaire even though comparisons will be made with previous studies to compare agreement on consistency. The R-MATS has a reported reliability coefficient of 0.82.

4.9.6 Validity

Joppe (2000:1) gave the following description of validity: “Validity determines whether the research truly measures that which it was intended to measure or how truthful the research results are. In other words, does the research instrument allow you to hit ‘the bull’s eye’ of your research object? Researchers generally determine validity by asking a series of questions and will often look for the answers in the research of others.” Creswell (2014) recommends that validity strategies be incorporated in the proposal. Among these strategies are member checking, using different data sources of information, clarification of the bias that the researcher brings in the study (i.e. the position of the researcher, gender, culture, etc); use of external auditor; and use of peer debriefing. In this study use was made of different data sources (learners, parents and educators), and use was also made of both quantitative and qualitative data.

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Researcher bias brought to the study was that the researcher was an outsider to the school and some parents were sceptical about how the information was going to be used, even though the purpose of the study was thoroughly explained. This could be part of the reasons why some parents did not allow their children to take part in the study. Peer debriefing was made use of in this study as well as an external auditor. To determine the reliability of the procedures the following reliability procedures have been suggested (Gibbs, 2007 cited in Creswell, 2014): check the transcripts for obvious mistakes, making sure there is no drift in the definition of the codes. After three weeks the researcher met with the 12 learners who formed the qualitative study group to verify the information they had provided in the interviews. Triangulation (use of both the quantitative and qualitative methods of data collection) was also used to establish corroboration of results. Triangulation is said to increase reliability, validity, or accuracy of a study (Knafl & Breitmayer, 1991).