Validity is in many ways the most important criterion of research and it is concerned with the integrity of the conclusions that are generated from a research (Bryman, 2012). A research instrument is valid if it measures what it is supposed to measure (Cohen et al., 2003; Van Wyk, 2007). The earlier view of what validity is, has changed over time, hence, Cohen et. al. (2007) admit that validity has taken many forms recently and that 100 percent validity cannot be achieved. They, as a result, advise that in quantitative data validity might be improved through careful sampling, appropriate instrumentation and appropriate statistical treatments of the data. All these stipulations by Cohen et al. were adhered to in this study to ensure its validity.
The first step in ensuring the validity of this study was in piloting the questionnaire (Appendix A) with a quota sample having similar characteristics as those for the actual study. The essence of the pilot study was to enable the researcher to check the wording and sequence of questions, the length of the questionnaire, clarity of instructions, and effectiveness of the cover letter. It also enabled the researcher to correct any inconsistencies and inaccuracies in the instrument to be used in the actual survey. As Bell (2008) puts it, the purpose of the pilot study is to get the ‘bugs’ out of the instruments so that respondents in the main study will experience no difficulties in completing it.
In using the quota sampling procedure and piloting the questionnaire, the researcher randomly selected ten EFAL teachers from outside the study area to respond to the questionnaire. After a week there was 80 percent response rate which makes the instrument valid in accordance to the standard set by Krejcie & Morgan (1970) that if 80 percent of the questionnaires to be used in the cross-sectional survey are returned, then the survey can be regarded as valid for piloting the instrument.
The responses from the piloted questionnaires indicated that the closed-ended questions were easy to understand and answer probably because; the closed-ended questions were all Likert scale, the questionnaire had been peer reviewed and
144
discussed with the supervisor severally. However, it became necessary to delete the few open-ended questions since respondents could not adequately answer them and the answer they provided needed to be probed into further. Though they were deleted from the questionnaire, they still appeared in the focus group discussion in order to help answer the research questions of the study effectively.
Secondly, a factor analysis (inferential statistics) was computed on the questionnaire in order to compare relationship sampling adequacy of the themes on the interview schedule -questions (Appendix B) and subsequent questions that were asked.
Cohen et. al. (2007) state that:
Factor analysis is a method of grouping together variables which have something in common. It is a process which enables the researcher to take a set of variables and reduce them to a smaller number of underlying factors which account for as many variables as possible. It detects structures and commonalities in the relationships between variables. Thus it enables researchers to identify where different variables in fact are addressing the same underlying concept (p.560).
The main motive for conducting the factor analysis in this final questionnaire (Appendix A) for this study was to identify how STAD is used in teaching EFAL. The way STAD has been broken into three parts under Section D of the questionnaire is indicative of how the factor analysis was conducted. In precise words; Principles of STAD, STAD and Teaching and Learning Subject outcomes are all looked into under the main variable- STAD in order to compare, find commonalities and summarize issues that emerged after the survey.
The third step in ensuring validity of the research instrument is content validity which refer to as the degree to which the contents of the test are representative of the applicable body of knowledge that it purports to cover (Van Wyk, 2007; Bryman, 2012; Cohen et al., 2007). Applying this to the questionnaire used in this cross-sectional
145
survey is a means of ensuring that the contents covered by this questionnaire are the different concepts found in the application of STAD in teaching EFAL in the KZN Province. It is for this reason that the researcher constructed questions under six broad sections in the questionnaire so that possibly nothing of importance will be left out in the data collection and subsequent analysis.
To strengthen the validity of this study an independent T-test was conducted to establish the variation between the responses of male and female respondents in relation to all the sections of the questionnaire, apart from the demographic data (Section A), in order to compare the responses given by the two genders. Additionally, ANOVA was computed and resulted to so as to identify the significance of the responses given in questions 4 and 6 in comparison to Sections B to F of the survey questionnaire. The statistical significance level of testing (p-value) was set at p=0.05 in all cases.
Again, the use of two totally different instruments in the data collection phase of the study, to a large extent helped in ensuring the validity of the study. Each of the instruments compensated for the weaknesses in the other instrument or complemented the strength of the other. The instruments also enhanced more credibility and produced different results that could easily be missed when a single instrument. The importance of the use of the survey questionnaire and focus group interview in the quantitative and qualitative phases of this study respectively, is made bare here. This strategy was very useful in ensuring the construct validity (Cohen et. al., 2007) of the study.
Concurrent validity, which gathers evidence to defend the use of a test for predicting other outcomes, was also used to validate this study. McIntire et al. (2005) are of the view that concurrent validity is demonstrated when a test correlates well with a measure that has previously been validated. They establish that the two measures in the study are taken at the same time. In a similar development, The Institute for Statistics Education (2013) added that The concurrent validity of survey instruments is a measure of agreement between the results obtained by the given survey instrument and the
146
results obtained for the same population by another instrument acknowledged as the "gold standard". It is for the reason of achieving concurrent validity that this study applied the sequential mixed method design which was applied in such a way that both the quantitative and qualitative approaches were given the same priority and data was collected with the cross-sectional questionnaire and the focus group discussion.
Lastly, the proportional stratified sampling procedure also helped in reducing sampling errors that could possibly bias the study and thus, affect the validity thereof. As established by Badu-Nyarko (2009:108), “this procedure helps to reduce sampling error to the extent that each stratum is homogeneous with regard to the variable of interest.” To achieve this, the researcher adopted the right sampling techniques at every stage where sampling was done all in a bid not to use a sampling technique or sample that might invalidate the study. After using the right sampling techniques to get the right sample and the other measures that have been put in place in this study, validity can be said to have been assured to a very large extent.