Software Reliability And Cost Model

This paper introduces the background and the development in the research field of software reliability. The basic concepts related to software reliability and reliability models are discussed. Then the comparative research on the existing software reliability models are brought out and several classic software models are enumerated. On this foundation, further research on software reliability and cost models have been done in this paper. The main results are as follows:1. This paper proposes a new software reliability model in which fault removal efficiency and fault occurrence efficiency are functions of testing time. In this model, imperfect debugging is considered in the sense that new faults can be introduced into the software during debugging and the detected faults may not be removed completely. Most software reliability growth models assume that the detected faults will eventually be removed and the fault occurrence efficiency is a constant. Consideration of fault removal efficiency and fault occurrence efficiency in the existing models is limited. The improved software reliability model is more practical.2. Upon the basis of the improved software reliability model, we present a software cost model with variable fault removal efficiency and fault occurrence efficiency. In this model, design cost during the software life cycle, test cost and maintenance cost are introduced together. At last, several conclusions in special circumstances and examples are given.3. A software cost model is proposed. Conventional software cost models assume that the time spent in removing a fault is negligible, and little attention is paid to the software reliability. These rigid assumptions limit the model's prediction precision and their application. We propose a software cost model incorporating fault-remove time which is followed exponential distribution and reliability function of software in this paper. At last, optimal release time is obtained by minimizing the cost function.