Miller G Edward, Gesn Paul Randall, Rotou Jourania
Division of Student Assessment, Texas Education Agency, 1701 N. Congress Avenue, Austin, TX, USA.
J Appl Meas. 2005;6(1):48-56.
In state assessment programs that employ Rasch-based common item linking procedures, the linking constant is usually estimated with only those common items not identified as exhibiting item difficulty parameter drift. Since state assessments typically contain a fixed number of items, an item classified as exhibiting parameter drift during the linking process remains on the exam as a scorable item even if it is removed from the common item set. Under the assumption that item parameter drift has occurred for one or more of the common items, the expected effect of including or excluding the "affected" item(s) in the estimation of the linking constant is derived in this article. If the item parameter drift is due solely to factors not associated with a change in examinee achievement, no linking error will (be expected to) occur given that the linking constant is estimated only with the items not identified as "affected"; linking error will (be expected to) occur if the linking constant is estimated with all common items. However, if the item parameter drift is due solely to change in examinee achievement, the opposite is true: no linking error will (be expected to) occur if the linking constant is estimated with all common items; linking error will (be expected to) occur if the linking constant is estimated only with the items not identified as "affected".
在采用基于拉施模型的共同项目链接程序的州评估项目中，链接常数通常仅根据那些未被确定存在项目难度参数漂移的共同项目来估计。由于州评估通常包含固定数量的项目，在链接过程中被归类为存在参数漂移的项目即使从共同项目集中移除，仍会作为可计分项目保留在考试中。在一个或多个共同项目发生项目参数漂移的假设下，本文推导了在链接常数估计中纳入或排除“受影响”项目的预期效果。如果项目参数漂移完全是由与考生成绩变化无关的因素导致的，那么在仅用未被确定为“受影响”的项目来估计链接常数的情况下，预计不会出现链接误差；如果用所有共同项目来估计链接常数，则预计会出现链接误差。然而，如果项目参数漂移完全是由考生成绩变化导致的，情况则相反：用所有共同项目来估计链接常数时，预计不会出现链接误差；仅用未被确定为“受影响”的项目来估计链接常数时，预计会出现链接误差。
