Roskam conjectured in 1985 that a general interpretation can be made for the a-parameter (slope) in an item response theory (IRT) analysis of personality inventories. That is, Roskam suggested that steeper slopes (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 this conjecture using item-total correlations and both two- and three-parameter IRT models with the Eysenck Personality Questionnaire and were unable to support Roskam's proposed interpretation.
Get full access to this article
View all access options for this article.
References
1.
Assessment Systems Corporation. (1989). User's manual for the ASCAL 2- and 3-parameter IRT calibration program. St. Paul, MN: Author.
2.
Eysenck, H. J. , & Eysenck, S.B.G. (1975). Eysenck Personality Questionnaire. San Diego, CA: EdITS/Educational and Industrial Testing Service.
3.
Ferrando, P. J. (1994). Fitting item response models to the EPI-A Impulsivity subscale. Educational and Psychological Measurement, 54, 118-127.
4.
Goh, D. S. , King, D. W., & King, L. A. (1982). Psychometric evaluation of the Eysenck Personality Questionnaire. Educational and Psychological Measurement, 42, 297-309.
5.
Helmes, E. (1980). A psychometric investigation of the Eysenck Personality Questionnaire. Applied Psychological Measurement, 4, 43-55.
6.
Holden, R. R. , Kroner, D. G., & Fekken, C. G. (1992). A model of personality test item response dissimulation. Journal of Personality and Social Psychology, 63, 272-279.
7.
Roskam, E. E. (1985). Current issues in item response theory: Beyond psychometrics. In E. E. Roskam (Ed.), Measurement and personality assessment (pp. 3-19). Amsterdam: Elsevier Science.
