AN EMPIRICAL-TEST OF ROSKAM CONJECTURE ABOUT THE INTERPRETATION OF ANICC PARAMETER IN PERSONALITY INVENTORIES

Roskam conjectured in 1985 that a general interpretation can be made f or the a-parameter (slope) in an item response theory (IRT) analysis o f personality inventories. That is, Roskam suggested that steeper slop es (and hence higher item-total correlations in classical test theory) will be found with more concretely worded items, whereas lower slopes will be found with more abstractly worded items. The authors tested t his conjecture using item-total correlations and both two-and three-pa rameter IRT models with the Eysenck Personality Questionnaire and were unable to support Roskam's proposed interpretation.