Abstract
The optimal time to release a software is a common problem of broad concern to software engineers, where the goal is to minimize cost by balancing the cost of fixing defects before or after release as well as the cost of testing. However, the vast majority of these models are based on defect discovery models that are a function of time and can therefore only provide guidance on the amount of additional effort required. To overcome this limitation, this paper presents a software optimal release model based on cost criteria, incorporating the covariate software defect detection model based on the Discrete Cox Proportional Hazards Model. The proposed model provides more detailed guidance recommending the amount of each distinct test activity performed to discover defects.