ISBN : 978-81-963532-2-3 (E-Book) 26 SOFTWARERELIABILITYANDQUALITYMANAGEMENT Repeatablevs.non-repeatablesoftwaredevelopmentorganization A repeatable softwaredevelopmentorganizationisone inwhichthesoftware developmentprocessisperson-independent.Inanonrepeatablesoftwaredevelopmentorganization,asoftwaredevelopmentprojectbecomessuccessfulpri marilyduetotheinitiative,effort,brilliance, or enthusiasm displayed by certain individuals. Thus, in a non-repeatable softwaredevelopment organization, the chances of successful completion of a software projectis to agreatextent depends on theteam members. SoftwareReliability Reliabilityofasoftwareproductessentiallydenotesitstrustworthinessordependability.Alternatively, reliability of a software product can also be defined as the probability of theproductworking“correctly”over a given period of time. Itisobviousthatasoftwareproducthavingalargenumberofdefectsisunreliable.Itisalsoclear that the reliability of a system improves, if the number of defects in it is reduced. However,there is no simple relationship between the observed system reliability and the number of latentdefects in the system. For example, removing errors from parts of a software which are rarelyexecutedmakeslittledifferencetotheperceivedreliabilityoftheproduct.Ithasbeenexperimentall y observed by analyzing the behavior of a large number of programs that 90% ofthe execution time of a typical program is spent in executing only 10% of the instructions in theprogram. These most used 10% instructions are often called the core of the program. The rest90% of the program statements are called non-core and are executed only for 10% of the totalexecution time.It therefore may not be very surprising to note that removing 60% productdefects from the least used parts of a system would typically lead to only 3% improvement to theproduct reliability. It 119 Software Engineering Keerthana P, Manasa KN, Ganga D Bengal
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