The Impact of Item Characteristics on Item and Scale Validity

This study describes the relation between personality items' validities, defined as the items' correlations with acquaintance ratings on the Big 5 personality factors, and other itemmetric properties including ambiguity, syntactic complexity, social desirability, content, and trait indicativity. Five external validity coefficients for each item on the California Psychological Inventory were correlated with a number of itemmetric variables often assumed to affect item validity. Item validity correlated positively with social desirability and trait indicativity and negatively with ambiguity across the five factors. Other characteristics had a more limited influence on item validity. Multiple regression analyses revealed trait indicativity -- how obviously an item response indicates a trait -- to be the most important determinant of item validity. Scales built from itemmetrically sound versus poor items showed differential validity in two additional samples. Implications for the psychological processes underlying responses to personality items are discussed.