Q. What are the assumptions of the execution-time component model? Compare the execution-time component for basic model and the logarithmic Poisson model.

Ans. The execution-time component is on the basis following assumptions

(1) Tests symbolize the environment in which the program will be used.

(2) Each failure is observed.

(3) Failure intervals are s-independent of each other.

(4) Hazard rate is a stable that changes at each fault correction.

(5) The failure rate is comparative to the s-expected value of the number of faults remaining.

(6) The fault-correction incidence rate is proportional to the failure-occurrence rate. Together rates are with respect to execution time.

The two models-basic execution time model as well as logarithmic Poisson execution time model- has failure intensity functions that differ as functions of execution time. Nevertheless the difference between them is best defined in terms of slope or decrement per failure experienced. The decrease in the failure intensity function remains constant for basic model while the decrement per failure decreases exponentially as shown in the following graph.