偵測受試者是否具有洩題資訊是維護測驗安全的首要任務，過去洩題的偵測主要是根據3PLM，並以lz指標來偵測受試者是否具有洩題資訊，結果發現lz有不錯的偵測成效。雖然如此，這些洩題的偵測僅考慮到受試者的作答反應，對於具有洩題資訊的受試者而言，其除了會答對難度超過其能力水準的試題外，還能快速作答，故作答時間應該也是洩題偵測的重要訊息。
本研究採用納入作答時間的4PLM，並以3PLM作為比較基礎，評估兩模式在各種洩題情境下的偵測成效。研究結果顯示，4PLM的偵測成效普遍優於3PLM，對低能力水準的受試者而言，其成效尤其顯著，因此，作答時間應可作為實務上洩題偵測的重要參考。

Test security can be improved when examinees with item pre-knowledge are effectively identified. To detect cheaters, the person-fit index, lz is commonly used. When item sharing occurs, examinees would answer difficult items correctly, but easy items incorrectly. Based on the aberrant response patterns, lz could be used to effectively identify examinees with item pre-knowledge. Nevertheless, response times could provide additional information for cheater detection because examinees would answer difficult items not only correctly but also quickly when they have item pre-knowledge. The purpose of this study is to improve the detection power of lz by using 4PLM, where response times were considered. The performance of the 4PLM was evaluated based on that observed from 3PLM. Results indicated that 4PLM performed better than 3PLM in identifying examinees with item pre-knowledge, especially for low ability examinees. Thus, not only item responses but also response times should be considered in identifying examinees with item pre-knowledge.