A general theory of software-reliability modeling

A general theory of software reliability that proposes that software failure rates are the product of the software average error size, apparent error density, and workload is developed. Models of these factors that are consistent with the assumptions of classical software-reliability models are developed. The linear, geometric and Rayleigh models are special cases of the general theory. Linear reliability models result from assumptions that the average size of remaining errors and workload are constant and that its apparent error density equals its real error density. Geometric reliability models differ from linear models in assuming that the average-error size decreases geometrically as errors are corrected, whereas the Rayleigh model assumes that the average size of remaining errors increases linearly with time. The theory shows that the abstract proportionality constants of classical models are composed of more fundamental and more intuitively meaningful factors, namely, the initial values of average size of remaining errors, real error density, workload, and error content. It is shown how the assumed behavior of the reliability primitives of software (average-error size, error density, and workload) is modeled to accommodate diverse reliability factors