RESULTS
4.2 Quantitative Results on Scale Validation
4.2.2 CFA, Convergent and Discriminant Validity, and Reliability
The results from EFA revealed that the challenge demands scale, the hindrance demands scale, and the job resources scale, included 12, 13, and 15 variables respectively, and were composed of four, three, and three dimensions respectively. In this phase, CFA was conducted to test whether the structures of the scales, based on the results of the preliminary factor analysis, were found in the results of the analysis with the new data (n = 211) or not. The AVE and CR values were calculated and the Chi- square difference tests were conducted to indicate the convergent and discriminant validity of the scales. In addition, Cronbach’s alpha coefficient analysis was conducted again to measure internal consistency reliability which indicates strong item covariance of the new scale (Hinkin, 2005). These analyses could provide evidence of the construct validity of the new scales.
4.2.2.1 Participants
The second subsample included 211 nurses. Participants were at the age between 22 and 60 years old (M = 33.17; SD = 7.57). Years of working experience were
between 1 and 40 years (M = 10.01; SD = 7.49). The majority of the participants were female (97%), were single (74%), completed no higher than a Bachelor’s degree (96%), and were in the staff level position (83%).
4.2.2.2 Results of Challenge Demands
In this study, criteria to determine an adequate fit of a model were as follows: the ratio of CMIN/df less than 5 (Bollen, 1989), CFI value greater than .90 (B.
Yang, 2005) and TLI value greater than .90 (Hair et al., 1998), RMSEA value less than .08 (Browne & Cudeck, 1993; Burnette & Williams, 2005), and SRMR value less than .08 (L. T. Hu & Bentler, 1999).
The CFA results of the 12-variable four-factor model of the challenge demands scale revealed that the goodness of fit was acceptable (CMIN/df = 2.25, CFI
= .94, TLI =.92, RMSEA = .08, and SRMR = .07). The range of factor loadings was between .53-.97 and was statistically significant at .01 level (see Figure 4.1). The values of AVE (i.e., a measure of convergence of a group of items indicating a latent construct) and CR (i.e., a measure of internal consistency among a set of items indicating a latent construct) of the scale were .56 and .94, which were higher than the recommended level of .50 and .70 (Fornell & Larcker, 1981; Hair et al., 1998) respectively, which might be concluded that the convergent validity of the instrument was adequate. The Chi-square difference test results of the 1-factor model with respect to the 4-factor model were significant (2 (6) =448.34, p < .01) which indicated that there was sufficient evidence that the discriminant validity (i.e., a factor in the scale is distinct from the others) of the challenge demands scale was acceptable (see Cohen, 1996) .
Figure 4.1 Confirmatory Factor Analysis of Four-Factor and 12-Variable Challenge Demands Scale (n = 211)
After the numbers of factors and their variables were stable, Cronbach’s alpha analysis was tested again. Results showed that item-total correlations ranged from .36-.61 and the scale, as well as each dimension, had acceptable internal consistency (
= .82; see Table 4.9).
Table 4.9 Cronbach’s Alpha Analysis of the Four-Factor Challenge Demands Scale
Scale/Factors No. of
items
Item-Total Correlation
Cronbach's alpha
Challenge Demands 12 .36-.61 .82
Job difficulty 3 .54-.79 .82
Time requirement 2 .48 .64
Patient and relative management 2 .88 .94
Within-organizational interaction 5 .44-65 .75
4.2.2.3 Results of Hindrance Demands
The CFA results of the 13-variable three-factor model of the hindrance demands scale, structured according to the results of EFA, revealed that the goodness of fit was unacceptable (CMIN/df = 3.54, CFI = .90, TLI =.87, RMSEA = .11, and SRMR = .07). In this regards, B. Yang (2005) suggested that although the outcomes of EFA emerge from the results of data analysis in preference to some predetermined concepts, the domain definitions could guide researchers to anticipate and select the number of factors that will be included in the final scale. Consequently, the author considered whether items of the same dimension have the same interpretable meaning or not. Finally, the author decided to separate the first factor including six variables into two factors (i.e., job difficulty and time requirement) including three variables each.
The new four factors of the hindrance demands scale was similar to the structure of the challenge demands scale. The CFA results of the 13-variable four-factor model of the hindrance demands scale revealed that the goodness of fit was acceptable (CMIN/df = 2.19, CFI = .96, TLI =.94, RMSEA = .08, and SRMR = .05). The range of factor loadings was between .61 and .98 and was statistically significant at .01 level (see Figure 4.2). The AVE and CR values of the scale were .62 and .95, which was concluded that the convergent validity of the instrument was adequate. The Chi-square difference test results of the 1-factor model with respect to the 4-factor model were significant (2 (6) =489.24, p < .01) which indicated that there was sufficient evidence that the discriminant validity of the hindrance demands scale was acceptable.
Figure 4.2 Confirmatory Factor Analysis of Four-Factor and 13-Variable Hindrance Demands Scale (n = 211)
Results of Cronbach’s alpha analysis showed that item-total correlations ranged from .55-.72 and the scale, as well as each dimension, had acceptable internal consistency ( = .90; see Table 4.10).
Table 4.10 Cronbach’s Alpha Analysis of the Four-Factor Hindrance Demands Scale
Scale/Factors No. of
items
Item-Total Correlation
Cronbach's alpha
Hindrance Demands 13 .55-.72 .90
Job difficulty 3 .69-.80 .87
Time requirement 3 .56-.68 .78
Patient and relative management 2 .90 .95
Within-organizational interaction 5 .60-.70 .84
4.2.2.4 Results of Job Resources
The CFA results of the 15-variable three-factor model of the job- resources scale revealed that the goodness of fit was unacceptable (CMIN/df = 3.98, CFI = .85, TLI =.82, RMSEA = .12, and SRMR = .05). Within each of the three subscales, modification indices suggested pairs of error terms that were likely to covary.
When some covariations were included in the model, the goodness of fit of the adjusted three-factor model was acceptable (CMIN/df = 1.50, CFI = .98, TLI =.97, RMSEA = .05, and SRMR = .04). The range of factor loadings was between .58-.89 and was statistically significant at .01 level (see Figure 4.3). The values of AVE and CR of the scale was .54 and .95, which was concluded that the convergent validity of the instrument was adequate. The Chi-square difference test results of the 1-factor model with respect to the 3-factor model were significant (2 (3) =363.98, p < .01) which indicated that there was sufficient evidence that the discriminant validity of the job resources scale was acceptable.
Figure 4.3 Confirmatory Factor Analysis of Three-Factor and 15-Variable Job Resources Scale (n = 211)
Results of Cronbach’s alpha analysis showed item-total correlations ranged from .32-.77 and the scale, as well as each dimension, had good internal consistency ( = .90; see Table 4.11).
Table 4.11 Cronbach’s Alpha Analysis of the Three-Factor Job Resources Scale
Scale/Factors No. of
items
Item-Total Correlation
Cronbach's alpha
Job Resources 15 .32-.77 .90
Supervisor Support 3 .52-.71 .76
Peer Support 4 .61-.70 .83
Organizational Support 8 .60-.73 .90