Exploring trait assessment of samples, persons, and cultures.

I present a very broad overview of what I have learned about personality trait assessment at different levels and offer some views on future directions for research and clinical practice. I review some basic principles of scale development and argue that internal consistency has been overemphasized; more attention to retest reliability is needed. Because protocol validity is crucial for individual assessment and because validity scales have limited utility, I urge combining assessments from multiple informants, and I present some statistical tools for that purpose. As culture-level traits, I discuss ethos, national character stereotypes, and aggregated personality traits, and summarize evidence for the validity of the latter. Our understanding of trait profiles of cultures is limited, but it can guide future exploration.