Cronbach’s alpha reflects the degree of the internal consistency of the items. The WPDI shows good internal consistency reliability across various studies, the Cronbach’s alphas ranged from .79 to .94 in a study conducted in 2013.
Content validity and face validity were examined in focus groups and individual interviews conducted from 2009 to 2011; convergent and discriminant validities, and concurrent validity were examined in the main study 2011. The validation results were found to be satisfactory.
For convergent validity, Rosenberg Self-esteem Scale (Rosenberg, 1965) was used to test the convergent validity of WPDI Self Appreciation. Pearson correlation between Rosenberg and WPDI Self Appreciation was .83 (p<.001). Depression Anxiety & Stress Scale (DASS) (Lovibond & Lovibond, 1995) and Chinese Positive Youth Development Scale –Emotional Competence (Shek, Siu & Lee, 2007) were used to test the validity of WPDI Emotional Health. Pearson correlation between DASS and WPDI Emotional Health was -.65 (p<.001) and correlations between PYDS-Emotional Competence and WPDI Emotional Health was .50 (p<.001).
Chinese Positive Youth Development Scale (Shek, Siu & Lee, 2007) – Bonding and Moral Competence were used to converge the validity of WPDI Family Relationship, Peer Relationship, and Moral Commitment, the correlations were .71, .69, and .62 respectively. All coefficients were significant at the .001 level.
The Chinese Spirituality Scale – Disorientation (Ng, Yau, Chan, Chan & Ho, 2005) was used to test WPDI Spiritual Quest and the correlation was .48 (p<.001). Global Perspective Inventory – Social Responsibility Scale (Braskamp, Braskamp. Merrill, & Engberg, 2010) was used to test convergent validity of WPDI Community Care and the correlation was .73 (p<.001). Again, this scale was found to be significantly correlated with WPDI Leadership with a Pearson correlation coefficient of .48 (p<.001) and WPDI Civic Responsibility with a Pearson correlation coefficient of .45 (p<.001).
For discriminant validity, the socially desirable response set (Hay, Hayashi, & Steward, 1989) was used to examine the discriminant validity of WPDI. The coefficients were significant and weak, ranging from .09 to .20, except Peer Relationship (r=.23), Moral Commitment (r=.25) and Spiritual Quest (r=.21). As to concurrent validity, the Satisfaction with Life Scale (Diener, Emmons, Larsen, & Griffin, 1985) was used and the correlations between the WPDI factors and satisfaction with life were significant.
For further details of WPDI psychometric properties, please refer to the following publication:
Ng, P., Su, X., Lai, G., Chan, D., Ho, E., Chan, V., Leung, H., Kwan, V., & Li, C. (2016). A holistic model of student development: The validation of Whole Person Development Inventory for college students in Hong Kong. Measurement and Evaluation in Counseling and Development, 0748175615625748.