Reliability
From August to December, 2008, PREP conducted a rigorous longitudinal and revalidation study on its personality scales to assess their reliability. Dr. Shaun Pichler and his team of researchers surveyed over 1200 individuals and collected complete data samples from 900 individuals from across the United States. Results indicated that the CORE™ scales were internally consistent, with reliabilities ranging from good (around .70) to excellent (above .80). These results again indicate that the PREP personality scales are effective in measuring the traits they are intended to measure, and differentiate persons based on their personality traits. The cross cultural component is currently underway in Chinese.
Validity
The PREP Personality Scales were also subjected to statistical testing to assess their validity using data from the 900 individuals surveyed as mentioned above. Confirmatory factor analysis, using LISREL 8.8, indicated that the survey items were successfully measuring the four CORE™ personality traits (e.g. RMSEA < .05), which supports the construct validity of the scales. Correlations with some of the Big Five personality dimensions further support the convergent validity of the scales. For instance, the Outgoing trait correlates strongly with Extraversion (r = .71, p < .05) and the Relaxed trait correlates moderately with Neuroticism (r - .48, p < .05). Correlations with validated scales measuring work-family conflict, interpersonal communication competence and generalized stress also support the criterion-related validity of the scales. For instance, persons who are relatively Relaxed tend to have less work-family conflict (r = -.10, p < .01), and less stress (r = -.30, p < .01); persons who are relatively Outgoing tend to have more interpersonal communication competence (r = .57, p < .01); individuals higher on Energy Reserve tend to have less stress (-.39, p < .01), better interpersonal communication competence (r = .57, p < .01), and higher career satisfaction (r = .32, p < .01); and individuals with higher personal expectations tend to have less stress (r = -.35, p < .01), higher interpersonal communication competence (r = .56, p < .01) and higher career satisfaction (r = .29, p < .01).
Demographics
In order to determine if individuals’ scores on the PREP personality scales vary as a function of racioethnicity, gender, education or age, all of the 16 scales used to assess personality dimensions were subjected to statistical analysis, comparing group means. When comparing Caucasian respondents to racioethnic minority respondents, results indicated that there was a significant between-group difference for only one scale, and that the magnitude of this difference was small. When comparing scores for individuals who are under 40 to 40 and older, there were significant between-group differences for only two scales, and these differences were again small in magnitude. Education was not correlated with scores on any of the scales, indicating that scores on the PREP scales do not vary with increasing (or decreasing) levels of education. This supports a basic principle of PREP: that scale items should be at an 8th grade reading level, and thus accessible to most people. When comparing men and women, there were significant between-group differences for six scales, but all of these differences were small in magnitude (i.e. absolute value around 1.0 out of at least 30 possible points). The magnitude of these differences are consistent with the magnitudes of gender differences found for other, validated personality scales, such as the NEO-PI.