The Mini-IPIP6: item response theory analysis of a short measure of the big-six factors of personality in New Zealand

This paper is the second in a series documenting and validating the Mini-IPIP6 for use in New Zealand. The Mini-IPIP6 is a public domain short-form personality instrument which provides four-item markers of the six broad-bandwidth dimensions of personality: Extraversion, Agreeableness, Conscientiousness, Neuroticism, Openness to Experience and Honesty-Humility. This study reports results from an Item Response Theory analysis of the Mini-IPIP6 in a nationally representative New Zealand sample (N = 5,576). A series of unidimensional graded item response models indicated that the Mini-IPIP6 provided well distributed estimates of each of the six dimensions of personality across the latent trait range and centered on the population mean. These findings indicate that the Mini-IPIP6 provides a reasonably precise measure of the major dimensions of personality, given the scale's brevity. Discrimination and difficulty parameter estimates for the Mini-IPIP6 in the New Zealand population are presented, along with Test Information Functions for each personality dimension. A copy of the Mini-IPIP6 is included.
There are a vast number of self-report personality measures available. Generally speaking, these measures are based on the assumption that '... individuals are characterized by stable, distinctive, and highly meaningful [...]