- In a software project, 10 errors were introduced in the Software Requirements

Question

- In a software project, 10 errors were introduced in the Software Requirements Specification document. All of those errors were amplified by a factor of 1:2 during the design phase where an additional 20 design errors were also introduced. All the errors from the design phase gets amplified 1:1.5 into code where lack of testing and review contributes to an additional 30 errors. If no requirements and design reviews are conducted, unit testing finds 30% of all errors, integration-testing finds 30% of the remaining errors, and validation tests find 50% of the remaining errors, then how many errors will be released to the field?

- In the above scenario, project manager decided to introduce requirements, design, and code reviews with 60% effectiveness in uncovering errors. How many errors will be released to the field?

- Consider the scenarios in Q1 and Q2. If each of the errors released to the field costs $4800 to find and correct, and each error found in review costs $240 to find and correct, then how much money is saved by conducting reviews?

Explanation / Answer

1. Requirement errors - 10
   Design errors - 20 + 10 *2 = 10 + 20 = 40
   Code errors - 40 * 1.5 = 60
   No requirement and design review - 60 + 30 = 90
  
   Unit testing found 30 % of all errors - 0.3 * 90 = 27
   Integration testing found 30% of remaining errors - 0.3 * 63 = 18.9 = 19
   Validation found 50% of remaining errors - 0.5 * (63-19) = 0.5 * 44 = 22
   Errors released will be 44 - 22 = 22

2. Design and Code review found 60% of released errors - 0.6 * 22 = 13.2 = 13
   Error released = 22-13 = 9

3. Scenario:
   Q1:
   In this total errors release is 22 so cost is 22*4800 = $105600
   if reviews have been conducted the errors released will be less as follows:
   We had code errors as 60 ans if reviews have been conducted then this total n would not have become 90 . But fixing those 30 has costed 30 * 240 = $7200.So with 60 as total errors the released errors are as follows:

   Unit testing found 30 % of all errors - 0.3 * 60 = 18
   Integration testing found 30% of remaining errors - 0.3 * 42 = 12.6 = 13
   Validation found 50% of remaining errors - 0.5 * (42-13) = 0.5 * 29 = 14.5 = 15
   Errors released will be 29 - 15 = 14
   So the cost will be 14 * 4800 =     $67200 + $7200 = $74400
   So the cost saved is 105600-74400 = $31200

   Q2:
     Had there been no review the number of errors released would have been 22 instead of 9.But those 13 have costed 13 * 240 = $3120. So with 9 the cost is 9 * 4800 = $43200+ 3120 = 46320 and with 22 released errors the cost is $105600. So review has saved 105600 - 46320 = $58280

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