| Table 3 SCALE® and ESAP® Cronbach’s alpha Reliability Statistics | |||||||
| SCALE® (N = 98) | ESAP® (N = 98) | ESAP® (2004, N = 1,389) | |||||
| α | No. Items | α | No. Items | α | |||
| Self-Esteem | 0.70 | 7 | 0.83 | 25 | 0.81 | ||
| Assertion | 0.75 | 7 | 0.82 | 18 | 0.60 | ||
| Comfort | 0.73 | 7 | 0.61 | 12 | 0.74 | ||
| Empathy | 0.85 | 7 | 0.90 | 12 | 0.79 | ||
| Drive Strength | 0.54 | 7 | 0.80 | 25 | 0.81 | ||
| Decision Making | 0.75 | 7 | 0.80 | 12 | 0.76 | ||
| Time Management | 0.86 | 7 | 0.91 | 12 | 0.82 | ||
| Influence | 0.71 | 7 | 0.81 | 12 | 0.82 | ||
| Commitment Ethic | 0.52 | 7 | 0.66 | 12 | 0.76 | ||
| Stress Management | 0.85 | 7 | 0.90 | 25 | 0.81 | ||
| Physical Wellness | 0.84 | 7 | N/A | N/A | N/A | ||
| Aggression* | 0.88 | 7 | 0.85 | 18 | 0.70 | ||
| Deference* | 0.83 | 7 | 0.89 | 18 | 0.75 | ||
| Change Orientation* | 0.77 | 7 | 0.84 | 12 | 0.75 | ||
Overall, the SCALE® provided strong evidence of internal reliability (Hammett, in press). The SCALE’s composite measure of Interpersonal skills (combining Assertion, Comfort, & Empathy) was high (α > .80), as were the composite measures of Career and Life Skills (combining Drive Strength, Decision Making, Time Management, Influence, & Commitment Ethic), and Personal Wellness (combining Stress Management & Physical Wellness). The Problematic Indicator composite (combining Aggression, Deference, & Change Orientation) was also high. Finally, the overall reliability when combining all items less those making up the Problematic Indicators was very high (α = .94). Overall based on these reliability statistics, it can be said that the SCALE® assessment reliably measures the global and composite skills constructs purportedly assessed by the instrument.
Reliability statistics for the ESAP® are also provided in Table 2. Including them was necessary because it was the instrument used for the SCALE® validity comparisons (Hammett, in press). Its baseline statistics for reliability may also be informative, therefore, as a comparison to SCALE®. Overall, the ESAP® yielded very high internal estimates of reliability with all composite scales exceeding α = .92. Finally, combining the ten skills resulted in a total instrument skills reliability of α = .96. One likely reason for the slightly higher composite scale alphas for the ESAP® compared to SCALE® is the increased number of items in each scale. Consider, for example, the 25 items that assess Stress Management for ESAP® compared to only 7 items for the same skill for SCALE®. As explained by Kaplan and Saccuzzo (2018),
1K ClubAccording to the domain sampling model, each item in a test is an independent sample of the trait or ability being measured. The larger the sample [of items representing the domain], the more likely that the test will represent the true characteristic. In the domain sampling model, the reliability of a test increases as the number of items increases. (p. 124).
