Cost of software quality ( software quality assurance )
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The document discusses the cost of software quality, emphasizing the need for economic assessment in software development and maintenance. It classifies quality-related costs into control costs, which aim to prevent software errors, and failure costs, incurred due to unaddressed errors, while also addressing managerial costs involved in project management. Various metrics are proposed to measure the effectiveness of software quality assurance systems within organizations.
Cost of software quality ( software quality assurance )
- 1. Software Quality Assurance Cost of Software Quality 1 Department of IEM, MSRIT
- 2. Cost of Software Quality cost of software quality – the economic assessment of software quality development and maintenance – is just another class of software quality metrics, where financial values are used as the measuring tool 2 Department of IEM, MSRIT
- 3. Objectives of cost of software quality metrics Managerial control over the cost of software quality is achieved by comparison of actual performance figures with: Control budgeted expenditures (for SQA prevention and appraisal activities) Previous year’s failure costs Previous project’s quality costs (control costs and failure costs) Other department’s quality costs (control costs and failure costs) 3 Department of IEM, MSRIT
- 4. After introducing changes in SQA procedures or SQA infrastructure, the following relations may provide better indications of the success of an SQA plan than those just mentioned: Percentage of cost of software quality out of total software development costs Percentage of software failure costs out of total software development costs Percentage of cost of software quality out of total software maintenance costs Percentage of cost of software quality out of total sales of software products and software maintenance 4 Department of IEM, MSRIT
- 5. The classic model of cost of software quality The classic quality cost model, developed in the early 1950s by Feigenbaum Provides a methodology for classifying the costs associated with product quality assurance from an economic point of view Developed to suit the quality situations found in manufacturing organizations 5 Department of IEM, MSRIT
- 6. The model classifies costs related to product quality into two general classes: Costs of control include costs that are spent to prevent and detect soft-ware errors in order to reduce them to an accepted level Costs of failure of control include costs of failures that occurred because of failure to prevent and detect software errors 6 Department of IEM, MSRIT
- 7. Costs of control are assigned to either the prevention or the appraisal costs subclass: Prevention costs include investments in quality infrastructure and quality activities that are not directed to a specific project or system, being general to the organization Appraisal costs include the costs of activities performed for a specific project or software system for the purpose of detecting software errors Failures of control costs are further classified into internal failure costs and external failure costs: Internal failure costs include costs of correcting errors that have been detected by design reviews, software tests and acceptance tests (carried out by the customer) and completed before the software is installed at customer sites. External failure costs include all costs of correcting failures detected by customers or the maintenance team after the software system has been installed 7 Department of IEM, MSRIT
- 8. The classic model of cost of software quality 8 Department of IEM, MSRIT
- 9. Prevention costs Typical preventive costs include: (1) Investments in development of new or improved SQA infrastructure components or, alternatively, regular updating of those components: Procedures and work instructions Support devices: templates, checklists, etc. (2) Regular implementation of SQA preventive activities: Instruction of new employees in SQA subjects and procedures related to their positions Instruction of employees in new and updated SQA subjects and procedures Certification of employees for positions that require special certification Consultations on SQA issues provided to team leaders and others. (3) Control of the SQA system through performance of: Internal quality reviews External quality audits by customers and SQA system certification organizations 9 Department of IEM, MSRIT Management quality reviews
- 10. Appraisal costs Appraisal costs are devoted to detection of software errors in specific projects or software systems. Typical appraisal costs cover: (1) Reviews: Formal design reviews (DRs) Peer reviews (inspections and walkthroughs) Expert reviews (2) Costs of software testing: Unit tests Integration tests Software system tests Acceptance tests (participation in tests carried out by the customer). (3) Costs of assuring quality of external participants, primarily by means of design reviews and software testing. These activities are applied to the activities performed by: Subcontractors Suppliers of COTS software systems and reusable software modules The customer as a participant in performing the project 10 Department of IEM, MSRIT
- 11. Internal failure costs Internal failure costs are those incurred when correcting errors that have been detected by design reviews, software tests and acceptance tests performed before the software has been installed at customer sites Typical costs of internal failures are: Costs of redesign or design corrections subsequent to design review and test findings Costs of re-programming or correcting programs in response to test findings Costs of repeated design review and re-testing (regression tests) 11 Department of IEM, MSRIT
- 12. External failure costs External failure costs entail the costs of correcting failures detected by customers or maintenance teams after the software system has been installed at customer sites Typical external failure costs cover: Resolution of customer complaints during the warranty period. In most cases, this involves a review of the complaint and transmission of instructions Correction of software bugs detected during regular operation Correction of software failures after the warranty period is over even if the correction is not covered by the warranty Damages paid to customers in case of a severe software failure detected during regular operation Insurance against customer’s claims in case of severe software failure 12 Department of IEM, MSRIT
- 13. The greater proportion of external failure costs hidden costs – reflect the indirect damages suffered by the software development organization as a result of those same failures Typical examples of hidden external failure costs are: Damages of reduction of sales to customers suffering from high rates of software failures Severe reduction of sales motivated by the firm’s damaged reputation Increased investment in sales promotion to counter the effects of past software failures Reduced prospects to win a tender or, alternatively, the need to under-price to prevent competitors from winning 13 Department of IEM, MSRIT tenders
- 14. An extended model for cost of software quality 14 Department of IEM, MSRIT
- 15. Managerial preparation and control costs Managerial preparation and control costs are associated with activities per-formed to prevent managerial failures or reduce prospects of their occurrence Typical managerial preparation and control costs include: Costs of carrying out contract reviews (proposal draft and contract draft reviews) Costs of preparing project plans, including quality plans and their review Costs of periodic updating of project and quality plans. Costs of performing regular progress control of internal software development efforts Costs of performing regular progress control of external participant’s contributions to the project 15 Department of IEM, MSRIT
- 16. Managerial failure costs Managerial failure costs can be incurred throughout the entire course of software development, beginning in the pre-project stage Typical managerial failure costs include: Unplanned costs for professional and other resources, resulting from underestimation of the resources upon which the submitted proposals are based Damages paid to customers as compensation for late completion of the project, a result of the unrealistic schedule presented in the company’s proposal Damages paid to customers as compensation for late completion of the project, a result of management’s failure to recruit sufficient and appropriate team members Domino effect: damages to other projects performed by the same teams involved in the delayed projects 16 Department of IEM, MSRIT
- 17. Application of a cost of software quality system In order to apply a cost of software quality system in an organization, the following are required: Definition of a cost of software quality model and array of cost items specifically for the organization, department, team or project Each of the cost items that constitute the model should be related to one of the sub-classes of the chosen cost of software quality model (the classic model or the extended model) Definition of the method of data collection. Application of a cost of software quality system, including thorough follow-up. Actions to be taken in response to the findings produced 17 Department of IEM, MSRIT
- 18. Thank you Presented by: Kiran Hanjar S 1MS12MIA03 III sem, IE MSRIT 18 Department of IEM, MSRIT