NotesFAQContact Us
Search Tips
Peer reviewed Peer reviewed
PDF on ERIC Download full text
ERIC Number: EJ1111284
Record Type: Journal
Publication Date: 2008-Mar
Pages: 19
Abstractor: As Provided
Reference Count: 12
ISSN: EISSN-2330-8516
Comparing Different Approaches of Bias Correction for Ability Estimation in IRT Models. Research Report. ETS RR-08-13
Lee, Yi-Hsuan; Zhang, Jinming
ETS Research Report Series, Mar 2008
The method of maximum-likelihood is typically applied to item response theory (IRT) models when the ability parameter is estimated while conditioning on the true item parameters. In practice, the item parameters are unknown and need to be estimated first from a calibration sample. Lewis (1985) and Zhang and Lu (2007) proposed the expected response functions (ERFs) and the corrected weighted-likelihood estimator (CWLE), respectively, to take into account the uncertainty regarding item parameters for purposes of ability estimation. In this paper, we investigate the performance of ERFs and of the CWLE in different situations, such as various test lengths and levels of measurement error in item parameter estimation. Our empirical results indicate that ERFs can cause the bias in ability estimation to fall within [-0.2, 0.2] for all conditions, whereas the CWLE can effectively reduce the bias in ability estimation provided that it has a good foundation to start from.
Educational Testing Service. Rosedale Road, MS19-R Princeton, NJ 08541. Tel: 609-921-9000; Fax: 609-734-5410; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A