測驗等化係指利用統計方法，將兩份或是兩份以上試卷的測驗分數進行校準。藉由等化處理技巧，不同測驗的結果可以轉換到同一量尺上，直接進行比較。在試題反應理論的假設下進行等化設計時，不同的測驗中，必須包含一部分的定錨試題，以便作為測驗間的連結之用。本研究探討定錨試題參數估計誤差分布範圍對受試能力估計精確性之影響。研究結果發現，定錨試題參數估計誤差的大小會直接反應在測驗等化後能力估計值上，其中又以難度參數含有估計誤差時影響較大；而增加測驗題數及定錨試題比例可降低等化的「均方誤差」（mean square error），測驗人數的多寡則影響不大，定錨比例為測驗題數的20%至30%等化效果最佳。

Test equating is a statistical process to adjust scores on different forms to the same scale, so that scores obtained on different forms can be compared to each other. According to the item response theory, while processing test equating, anchor items must be involved in different tests, so that they can be served as a link among these tests. This research aims to investigate the impacts of estimating error distributions in anchor item parameters on test equating. The result shows that the measurement error in the anchor items can be directly reflected on the test equating, which has greater impact when the difficulty parameters have estimation errors; and increasing test items can reduce bias during test equating, while the amount of the tested has not much impact, and finally, the equating of the anchor shows the best effect when it takes up to 20% to 30% of test items.