Cost Impact of Software Defects
IEEE Standard Dictionary of Electronics and Electrical Terms IEEE Standard 100-1992 describe a defect as a product anomaly. This definition is for fault in the hardware context can be got in the year of IEEE Standard 6 (10.12-1990);
(a) A defect in a hardware component or device or; example for, a broken wire or a short circuit. (b) An incorrect step data or process definition in a computer program. Note this definition is defined primarily through the fault tolerance discipline. In common usage the terms bug and error are used to express this meaning See also program-sensitive fault; data sensitive fault; equivalent faults; fault masking; intermittent fault.
Within the context of the software procedure the terms fault and defect are synonymous. They both imply a quality problem which is discovered after the software has been published to end users. In the earlier chapters we used the term error to depict a quality problem which is discovered through software engineers or others before the software is released to the end user.
The primary goal of formal technical reviews is to search errors during the process so which they do become error after publish of the software. The general advantage of formal technical reviews is the early discovery of errors so which they do not propagate to the next step in the software procedure.
A number of companies' studies like Nippon Electric, TRW, and Mitre Corp., between others indicate which design activities introduce among 50 and 65 % of all bugs and ultimately all defects during the software procedure. Moreover, formal review methods have been shown to be up to 75 % effective [JON86] in uncovering design flaws. Through removing and detecting a huge percentage of these bugs, the review procedure substantially reduces the cost of subsequent steps in the maintenance and development phases.
To describe the cost impact of a previous error detection we have to consider a series of relative costs which are based on actual cost data collected for huge software projects [IBM81] Suppose that an error uncovered during design will cost 1.0 monetary unit to correct. By Relative to this cost, the similar error uncovered just before testing commences will cost 6.5 units during testing 15 units and after release among 60, 100 units.