Abstract
In this paper,the reliability function was estimation by the robust bayes approach using the initial distribution of the parameter 𝜃 with class (ML-II-𝜀-contaminated) when the shape parameter β is known and under the quadratic loss function for the duration of gastric ulcer patients since diagnosis and treatment until recovery and hospital discharge or death. The time of patient's admission to diagnosis and treatment was truncated. It was found that the data follow the two-parameter Weibul distribution (𝜃,β) where the prior
distribution of the scale parameter was two-parameter Fréchet distribution (α0=1,𝜎0) according to prior information from previous years about the length of hospital stay and the opinions doctors and specialists.