Experts values, Cronbach Alpha and CITC for DEMATEL model
Questionnaire. The 12 failure modes served as indices in the development of the DEMATEL questionnaire. A 7-point scale was adopted for the scoring system, where 6 represented the highest effect and 0 represented no effect. The respondents to the DEMATEL questionnaire were the 9 experts that participated in the FMEA survey. The content was explained to the respondents before the questionnaires were administered. All the questionnaires were retrieved, for a retrieval rate of 100%. The table 3 shows the direct relation matrix, which is the same as pairwise comparison matrix of the experts. Before we create Initial direct-relation matrix, we calculated Cronbach's alpha and CITC based on questionnaires from experts. Cronbach’s alpha was applied to test the reliability of the data collected from the questionnaires in this research. The test results revealed that the questionnaires used in the DEMATEL analyses are reliable (since exceeds 0.7). The Cronbach’s alpha value in this research was 0.9971. In this research, the consistency between the survey results will be examined when a group of experts are invited to participate in the DEMATEL survey. Corrected item-total correlation was applied to evaluate the internal consistency of the questionnaire, and it was considered acceptable for the standard of 0.30 (Bernstein, 1994). There are total of 9 experts who joined and shared their opinions regarding this research. The value of corrected item-total correlation can be computed by the Pearson product-moment correlation coefficient. In general, the respondent with the smallest corrected item-total correlation value below 0.30 will be removed and the values of corrected item-total correlation will be calculated again until all the values of corrected item-total correlation for the remaining items are above 0.3. However, all the corrected item-total correlation values are above 0.3 in this research, which means the survey results are very consistent. Thus, no respondent has been removed. The values of corrected item-total correlation for the 9 experts were listed in Table 2 below.