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Approximate expressions for parameter estimates in the Rasch model
Author(s) -
Cohen Leslie
Publication year - 1979
Publication title -
british journal of mathematical and statistical psychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.157
H-Index - 51
eISSN - 2044-8317
pISSN - 0007-1102
DOI - 10.1111/j.2044-8317.1979.tb00756.x
Subject(s) - rasch model , polytomous rasch model , simple (philosophy) , wright , mathematics , maximum likelihood , item response theory , computer science , statistics , psychometrics , philosophy , epistemology , programming language
The Wright‐Panchapakesan (1969) maximum‐likelihood equations for estimating the ability and difficulty parameters in the Rasch model have hitherto required an iterative procedure for their solution. In this paper the equations are solved approximately and simple closed forms are established which give values close enough for most practical purposes to those obtained by iteration. The results are illustrated with reference to a 50‐item physics test.