This study was designed to measure the relative effectiveness of two models of equating test difficulty; the Linear Model, Design IV, and the Rasch Model. The context of the comparison was that of increased mean and decreased standard deviation for the second administration of a test. It was expected that the Linear Model would be less effective than the Rasch Model since it includes the mean and the standard deviation in its formulation and the Rasch Model does not. It was expected that the relative effectiveness of the Rasch Model would increase as the difference between test means increased. / Two types of anchor tests were evaluated. One consisted of items of moderate difficulty and the other of items with extreme difficulties. The anchor test with extreme difficulties was viewed as representing 'worst case' specification and it was therefore expected that the moderate set would perform better than the extreme set. / The results indicated that when the entire score scale is of concern the Rasch Model is superior to the Linear Model with both the moderate and extreme anchor tests. At the section of the score scale typically used for cut-off scores for minimal competency tests, the Rasch Model is superior in producing small levels of bias, but the Linear Model produces lower levels of error. The equating discrepancies produced by the Rasch Model average near zero but fluctuate relatively widely around that point. Linear Model equating discrepancies show a negative bias but fluctuate less than for the Rasch Model. The Linear Model was more affected by changes in mean and standard deviation than was the Rasch Model. In the area of the score scale typically used for cut-off scores the difference in results for the anchor tests is small enough so that latitude in selecting common items is warranted. / Source: Dissertation Abstracts International, Volume: 45-09, Section: A, page: 2847. / Thesis (Ph.D.)--The Florida State University, 1984.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75374 |
| Contributors | CALDWELL, LESLIE JONES., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 114 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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