title: Estimation of the accessibility of items and the confidence of candidates: a Rasch-based approach.
abstract: In Scottish High School mathematics examinations partial credit is normally awarded for answers which are not totally correct but nevertheless contain some of the correct working. As a way of incorporating partial credit in the marking of ICT versions of these examinations, "steps" have been introduced. The use of "steps" also allows for a Rasch analysis that measures the inaccessibility of items and the confidence of candidates in addition to the traditional difficulty of items and ability of candidates. Two Rasch models can be fitted and jointly assessed for fit. The resulting measures can then be investigated for any relationship between ability and confidence and between difficulty and inaccessibility. A small data set has been used to illustrate these ideas.
authors.affiliation: Heriot-Watt University. a.a.korabinski@ma.hw.ac.uk
authors.forename: A A
authors.initials: AA
authors.lastname: Korabinski
authors.forename: M A
authors.initials: MA
authors.lastname: Youngson
authors.forename: M
authors.initials: M
authors.lastname: McAlpine
mesh_terms: D003627:Data Interpretation, Statistical; D004521:Educational Measurement / Q000706:statistics & numerical data*; D006801:Humans; D008433:Mathematics; D015233:Models, Statistical; D012606:Scotland