## 3 Results
### Defining Internal Consistency and Construct Validity of the PDATL Scale  
#### 3.2.1 The Study 1-NKUA  
Reliability analysis was performed at a significance level of \(\alpha\) = 0.05 for the study1-NKUA data set. Cronbach's \(\alpha\) coefficient and corrected item-total correlations were used to explore the inter-relationship of all nine items and identify redundant questions. [PERSON]'s \(\alpha\) coefficient was 0.92, and all items were found to contribute to the scale significantly for this data set. Thus, all items were considered unidimensional, strongly associated with each other, and represented a single concept [12]. Principal Component analysis using a Varimax with Kaiser Normalization rotation, at a significant level of 0.05, was subsequently performed to test the questionnaire's internal structure regarding its pattern and structure matrix; thus, appropriate for data reduction, enabling the removal of redundant questions [2]. For each factor, for the loading value (the percentage of variance in an original variable explained by a factor) to be considered significant based on the sample size of this data set, the factor loading coefficient was set at 0.45 for the study 1-NKUA. In this data set, three principal components explained the total variance of 82% (Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO) was 0.86, and Bartlett's Test of Sphericity (BTS) Sig = 0.00). The KMO results indicated that the identified three underlying grouping factors (components) appropriately explained the correlations between variables. The grouping factors were component (1): items 1,2,3, component (2): items 4,5, and 6, and component (3): items 7, 8, and 9. Moreover, the BTS results indicated that the formulated null hypothesis assuming that the existing correlation matrix is not different from an identity matrix and therefore questions would be unrelated, was rejected (\(p\) < 0.05) and confirmed the offered correlations. In light of establishing higher standards for the formulated scale, new tests were performed by splitting the samples by gender and age using all nine items [2]. It was proved that the loading pattern was similar for both age groups, females, participants with mixed dentitions consisting of functional tooth units (FTUs) on artificial teeth, and participants having their dentures in use between 2 and 3 years. The complete denture wearer group was potentially small for item 4 to contribute to the measurement model. Moreover, item 4 did not contribute to factor loading in recent both partial and complete denture wearers. Additionally, although males were a large group of participants, item 9 did not contribute to the factor model in the male group. Reliability analysis was rerun after removing items 4 and 9 at a significant level of 0.05. [PERSON]'s \(\alpha\) coefficient and corrected item-total correlations were again used to reveal the potential existence of low contribution items in the scale and remove them. [PERSON]'s \(\alpha\) coefficient was 0.89, slightly lower, but all seven items excellently contributed to the scale. Principal Component analysis using a Varimax with Kaiser Normalization rotation, at a significant level of 0.05, was again performed to test the 7-item scale's internal structure regarding its pattern and structure matrix. In this 7-item scale, three principal components were highlighted that explained the total variance of 87% (Kaiser-Meyer-Olkin Measure of Sampling Adequacy KMO = 0.80 and Bartlett's Test of Sphericity (BTS) Sig = 0.00) (Table 4).