Project Runway Supermodel Rayleigh
Move over Heidi, Kate and Cindy, if we are talking about software reliability, this model will surely dominate the runway. Supermodel Rayleigh.
A model of software reliability, the Rayleigh model is a parametric model in the sense that it is based on a specific statistical distribution. When the parameters of the statistical distribution are estimated based on the data from a software project, projections about the defect rate of the project can be made based on the model.
The Rayleigh model is a special case of the Weibull distribution family, which has been widely used for reliability studies in various fields. Supported by a large body of empirical data, software projects were found to follow a life-cycle pattern described by the Rayleigh curve, for both resource and staffing demand and defect discovery/removal patterns. The Rayleigh model is implemented in several software products for quality assessment. It can also be implemented easily via statistical software packages, such as the example provided in this chapter.
Compared to the phase-based defect removal model, the Rayleigh model is a formal parametric model that can be used for projecting the latent software defects when the development work is complete and the product is ready to ship to customers. The rationale behind the model fits well with the rationale for effective software development. Specifically, while the defect removal effectiveness approach focuses on defect removal, the Rayleigh encompasses both defect prevention (reduction in defect rates) and early defect removal.
In addition to quality projection, another strength of the Rayleigh model is that it provides an excellent framework for quality management.