Open AccessAN UPPER ASYMPTOTE FOR THE THREE‐PARAMETER LOGISTIC ITEM‐RESPONSE MODEL *
Author(s) -
Barton Mark A.,
Lord Frederic M.
Publication year - 1981
Publication title -
ets research report series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.235
H-Index - 5
ISSN - 2330-8516
DOI - 10.1002/j.2333-8504.1981.tb01255.x
Subject(s) - asymptote , statistics , mathematics , estimation theory , item response theory , logistic regression , model parameter , shape parameter , maximum likelihood , mathematical analysis , psychometrics
An upper‐asymptote parameter was added to the three‐parameter logistic item response model. This four‐parameter model was compared to the three‐parameter model on four data sets. The fourth parameter increased the likelihood in only two of the four sets. Ability estimates for the students were generally unchanged by the introduction of the fourth parameter.