本文研究串聯及併聯產品之故障率估計,估計方法有兩種,即直接估計及間接估計,均為無母數估計。我們用均方差來比較二種估計之優劣。 The hazard rates of two components assembly products can be estimated directly and indirectly. We compare these two estimation procedures based on mean square error. The estimators considered are constructed from kernel density estimators and empirical distributions.