ERIC Number: ED435737
Record Type: Non-Journal
Publication Date: 1999-Nov
Reference Count: N/A
The Relationship between the Bock-Aitkin Procedure and the EM Algorithm for IRT Model Estimation.
Hsu, Yaowen; Ackerman, Terry A.; Fan, Meichu
It has previously been shown that the Bock-Aitkin procedure (R. Bock and M. Aitkin, 1981) is an instance of the EM algorithm when trying to find the marginal maximum likelihood estimate for a discrete latent ability variable (latent trait). In this paper, it is shown that the Bock-Aitkin procedure is a numerical implementation of the EM algorithm for a continuous latent ability variable using numerical quadrature. Further, the relationship between the EM algorithm, marginal maximum likelihood estimation, and the Bock-Aitkin procedure is described for both the discrete and continuous cases. Some issues concerning the use of the Bock-Aitkin procedure and the EM algorithm are addressed. (Contains 31 references.) (SLD)
Descriptors: Equations (Mathematics), Estimation (Mathematics), Item Response Theory, Mathematical Models, Maximum Likelihood Statistics
ACT Research Report Series, P.O. Box 168, Iowa City, IA 52243-0168.
Publication Type: Reports - Evaluative
Education Level: N/A
Authoring Institution: American Coll. Testing Program, Iowa City, IA.