在傳統的壽命試驗中，通常不允許在試驗中間移除存活之元件。但是，在實務上實驗者有時候必須於試驗中間移除部分的存活元件。因此，逐步設限便被用來處理這種類型的問題。此外，由於試驗操作上的限制，使得有些試驗無法連續地觀察受測試元件的狀況，只能每隔一段時間來記錄有多少個元件發生故障，因此無法知道這些元件的確切故障時間，這種型態的資料稱為分群資料。再則由於科技的發達使得元件的可靠度不斷的提昇，所以在有限的試驗時間內可觀察到的故障元件個數便很少甚至沒有故障元件發生，因此加速壽命試驗的方法可讓實驗者快速獲得足夠的元件壽命資料，以便於研究產品的可靠度相關問題。本文將逐步設限和分群資料的觀念結合，提出逐步型一分群設限加速壽命試驗的方式，探討元件壽命為韋伯分配時，在有限的試驗預算下，以非線性混合整數規劃方法來找出最佳的試驗配置，並舉例子來闡述所提出的方法，以及探討分配和成本參數變動時的敏感度分析。
In traditional censoring life test, it is not allowed for surviving units to be removed from the test at points other than the final termination point. However, this allowance will be desirable for some experimenters. Therefore, a progressive censoring scheme is proposed to handle this problem. Besides, in practice, it is often impossible continuously to observe or inspect the testing process. We can only record whether a test unit fails in an interval instead of measuring failure time exactly. Hence, the test units are inspected intermittently. Data of this type are called grouped data. Moreover, with today's high technology, some life tests result in few or no failures in a short life testing time. One approach to solve this problem is to accelerate the life of units by increasing the levels of stress in order to obtain failures quickly. In this paper, we combine progressive censoring, grouped data and step-stress accelerated life test to develop a progressively type-I group-censored step-stress test plan. We use the nonlinear mixed integer programming to obtain the optimal settings of the test plans for Weibull lifetime distribution under cost constraint. A numerical example is studied to illustrate the proposed approach and sensitivity analysis is performed.
