The purpose of this study is to analyze the predictive power of the ability
estimates obtained through the two-parameter IRT model on the English
Proficiency Exam administered at BaSkent University in September 2001
(BUSPE 2001). As prerequisite analyses the fit of one- and two-parameter
models of IRT were investigated.
The data used for this study were the test data of all students (727) who took
BUSPE 2001 and the departmental English course grades of the passing
students.
At the first stage, whether the assumptions of IRT were met was
investigated. Next, the observed and theoretical distribution of the test data
was reviewed by using chi square statistics. After that, the invariance of
ability estimates across different sets of items and invariance of item
parameters across different groups of students were examined.
At the second stage, the predictive validity of BUSPE 2001 and its subtests
was analyzed by using both classical test scores and ability estimates of the
better fitting IRT model.
The findings revealed that the test met the assumptions of
unidimensionality, local independence and nonspeededness, the
assumptions of equal discrimination indices was not met. Whether the
assumption of minimal guessing was met remained vague. The chi square
statistics indicated that only the two parameter model fitted the test data.
The ability estimates were found to be invariant across different item sets
and the item parameters were found to be invariant across different groups
of students.
The IRT estimated predictive validity outweighed the predictive validity
calculated through classical total scores both for the whole test and its
subtests. The reading subtest was the best predictor of future performance in
departmental English courses among all subtests.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/1217629/index.pdf |
| Date | 01 January 2003 |
| Creators | Yapar, Taner |
| Contributors | Berberoglu, Giray |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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