caa a22 4500 606241914 CHVBK 20210128101315.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s11336-014-9405-1 doi (NATIONALLICENCE)springer-10.1007/s11336-014-9405-1 Saddlepoint Approximations of the Distribution of the Person Parameter in the Two Parameter Logistic Model [Elektronische Daten] [Martin Biehler, Heinz Holling, Philipp Doebler] Large sample theory states the asymptotic normality of the maximum likelihood estimator of the person parameter in the two parameter logistic (2PL) model. In short tests, however, the assumption of normality can be grossly wrong. As a consequence, intended coverage rates may be exceeded and confidence intervals are revealed to be overly conservative. Methods belonging to the higher-order-theory, more specifically saddlepoint approximations, are a convenient way to deal with small-sample problems. Confidence bounds obtained by these means hold the approximate confidence level for a broad range of the person parameter. Moreover, an approximation to the exact distribution permits to compute median unbiased estimates (MUE) that are as likely to overestimate as to underestimate the true person parameter. Additionally, in small samples, these MUE are less mean-biased than the often-used maximum likelihood estimator. The Psychometric Society, 2014 small-samples nationallicence saddlepoint approximation nationallicence Lugannani-Rice nationallicence modified signed likelihood ratio statistic nationallicence higher-order-theory nationallicence parameter distribution nationallicence 2PL nationallicence exponential family nationallicence person parameter nationallicence confidence intervals nationallicence median unbiased estimator nationallicence mean-bias nationallicence Biehler Martin Westfälische Wilhelms-Universität Münster, Münster, Germany aut Holling Heinz Westfälische Wilhelms-Universität Münster, Münster, Germany aut Doebler Philipp Westfälische Wilhelms-Universität Münster, Münster, Germany aut Psychometrika Springer US; http://www.springer-ny.com 80/3(2015-09-01), 665-688 0033-3123 80:3<665 2015 80 11336 https://doi.org/10.1007/s11336-014-9405-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11336-014-9405-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Biehler Martin Westfälische Wilhelms-Universität Münster, Münster, Germany aut NATIONALLICENCE 700 1- Holling Heinz Westfälische Wilhelms-Universität Münster, Münster, Germany aut NATIONALLICENCE 700 1- Doebler Philipp Westfälische Wilhelms-Universität Münster, Münster, Germany aut NATIONALLICENCE 773 0- Psychometrika Springer US; http://www.springer-ny.com 80/3(2015-09-01), 665-688 0033-3123 80:3<665 2015 80 11336