NotesFAQContact Us
Search Tips
Peer reviewed Peer reviewed
PDF on ERIC Download full text
ERIC Number: EJ1111599
Record Type: Journal
Publication Date: 2007-Dec
Pages: 24
Abstractor: As Provided
ISSN: EISSN-2330-8516
The Impact of Anchor Test Length on Equating Results in a Nonequivalent Groups Design. Research Report. ETS RR-07-44
Ricker, Kathryn L.; von Davier, Alina A.
ETS Research Report Series, Dec 2007
This study explored the effects of external anchor test length on final equating results of several equating methods, including equipercentile (frequency estimation), chained equipercentile, kernel equating (KE) poststratification PSE with optimal bandwidths, and KE PSE linear (large bandwidths) when using the nonequivalent groups anchor test (NEAT) design. This study used pseudotests constructed of item responses from a real operational test. The equating methods were evaluated using an equating criterion. Conditional differences between the criterion scores and equated scores, and root mean square error of the differences (RMSE) were used as measures to compare the methods to the criterion equating, which in this study is an equivalent groups (EG) equipercentile equating function. The results indicate that bias tended to increase in the conversions as the anchor test length decreased, but the KE PSE with optimal bandwidths and equipercentile (frequency estimation) methods were less sensitive to this change than the other methods. The KE PSE linear method with large bandwidths performed poorly compared to the criterion across all anchor test lengths. [This paper was originally presented at the annual meetings of the American Educational Research Association (AERA) and the National Council on Measurement in Education (NCME), held between April 10 and April 12, 2006, in San Francisco, CA.]
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; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A