本研究探討電腦適性測驗中試題曝光率控制法the sympson and Hetter conditional procedure (SHC法)對曝光率有效控制的程度，並與其他兩種常用的方法—the Davey and Parshall procedure(DP法)與the Stocking and Lewis conditional multinomial procedure (SLC法)的特性與功能作比較。整個研究採用電腦程式模擬電腦適性測驗程序，使用四個不同大小的題庫以及二種最大曝光率期望值進行。評鑑的標準包話最大曝光觀察值、試題重複出現率、題庫使用度、以及測量標準率。另外，本研究亦針對做計曝光率控制參數所需之最小樣本數進行探討。結果顯示，SHC法最能控制試題曝光率至研究中之期望值以及降低試題重複出現率，其次是SLC法。而DP法對於題庫的使用度整體而言是最佳的。研究的結果提共了對曝光率控制法更清楚的認識。

　　　　　 This study examined the effectiveness of the Sympson and Hetter conditional (SHC)procedure, a modification of the Sympson and Hetter algorithm, in controlling the exposure rates of items in the CAT environmet. Its properties were compared with those of the Davey and Parshall (DP) and the Stocking and Lewis conditional multinomial (SLC) procedures. Simulations were used to carry out this research. The advantages and disadvantages of these strategies were considered under four item pool sizes and two desired maximum exposure rates and were evaluated in light of maximum observed exposure rates, test overlap rates, utilization of the item pool, and conditional standard errors of measurement. Also, the issue of the appropriate conditional sample sizes in deriving the exposure control parameters was considered in the present study. The results showed that the SHC procedure bets served the purpose of controlling the observed exposure rates to the desired values and yielding the lowest overlap rates, followed by the SLC method. The DP method utilized the item pools to a satisfactory extent overall. The results of this study have offered a clearer understanding of the properties of the exposure control methods.