Temperament refers to basic dimensions of personality that are grounded in biology and explain individual differences in the developmental process rather than universal dynamics. Temperament is currently an active area of research with documented applicability to a variety of developmental and mental health outcomes such as conscience formation,…

Over the last 15 years or so, research into measurement error has begun to consider not just whether the test items fit, but whether the people who answer the items fit. Attempts to systematically identify people who do not fit the typical pattern have led to several "person-fit statistics." This digest describes the need for such…