在存活分析中，觀察到的數據資料常是一個區間而不是一個點。例如血有病患者輸到不潔的血液後在六個月後檢查並無HIV，但在一年後檢查卻有，所以很顯然對這個病人而言HIV 的潛伏期應在六個月到一年之間，亦即時間區間為(6,12)。諸如此類的觀察值便稱做區間資料。
本篇論文考慮在參數型態下，以動差估計法的觀點發展一個近似估計法來估計參數，然後應用在指數分配及韋伯分配。並經由模擬和實例子與Dain(1995)的幾種估計方法做比較。

In survival data analysis , exact event times are sometimes not ascertainable. For example , an hemophiliac has received contaminated blood with
HIV . After six months , his blood test shows HIV negative , but HIV positive after one year . Therefore , the observation of HIV incubation is (6,12] . This kind of observation is called interval data.
The purpose of this thesis is to propose an approximation mehod by the idea of method of moment estimation .We apply it to the exponential distribution and the Weibull distribution .We also compare it with the methods using in Dain(1995) via simulation and example.

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