ABSTRACT
A software reliability model specifies the general form of
the dependence of the failure process on the principal
factors that affect it: fault introduction, fault removal, and
the operational environment. The failure rate (failures per
unit time) of a software system is generally decreasing due
to fault identification and removal. However, it is possible
for the failure rate to increase as a result of design changes
or the introduction of new faults when correcting old faults.
In general, the assumption of reliability models is that the
trend of the failure rate decreases over time. This has been
observed in practice. Software reliability modeling is done
to predict future failure rate and other reliability metrics.
Two reasons for the predictions are: 1) to predict the
execution time during test that is required to meet a speci-
fied reliability objective and 2) to predict the reliability of
the software when the product is released.
