4 a )with regard to the cost of software quality , explain each of the following
ID: 3636343 • Letter: 4
Question
4a )with regard to the cost of software quality , explain each of the following terms and compare and contrast the effect each may have on the cost of a software project . Give two example of each to support your answer
1- internal failure costs
2- external failure costs
3- prevention costs
4- detection costs
b ) according to Crosby , “ Quality is Free “ . with reference to Prevention cost and detection coast ( from part a above ) , discuss whether you agree with Crosby's statement .
C ) assume that , because of your expertise in software quality and software quality assurance , you have just been hired into a newly created position by the maneger of an orgnisation which is experiencing difficulty several development . Recently , they have delivered several products which are technically sophisticated , but have developed a reputation for poor reliability in the view of the customer . The organisation is divided into groups along project lines with a senior technical person leading each project . The software development are talent people but there appears to be no systematic control of the development process and a lack of consistency in the methods employed within projects and between different project . Your boss expects you to get things turned around quickly . What are you going to do ? Be realistic ! Analyse the consequences of your recommended action
d ) identify two kinds of technical reviews that should take place in a well-managed software development project . Discuss briefly the contribution of each kind of review .
Explanation / Answer
1.Internal failure costs come from deficiencies discovered before delivery. These include all the costs associated with the failure (nonconformities) to meet the needs of your external and internal customers. This failure cost is one of the 4 key components of quality costs. Examples of Internal Failure Costs : Scrap: The labor, material, and (usually) overhead that created the defective product. The item cannot be economically repaired. The titles are numerous?scrap, spoilage, defectives, etc. Rework: The cost to correct the defective material or errors in service products. Lost or missing information: The cost to retrieve this expected information. Failure analysis: The cost analyzing nonconforming goods or services to determine the root causes. Supplier scrap and rework: Scrap and rework costs due to nonconforming product received from suppliers. This includes the costs to the buyer of resolving the supplier quality problems. 100% sorting inspection: The cost of completing 100% inspection to sort defective units from good units. Retest: The cost to retest products after rework or other revision. Changing processes: The cost of modifying the manufacturing or service processes to correct the deficiencies. Redesign of hardware: The cost to change designs of hardware to correct the issues. Redesign of software: The internal cost to changing software designs. Scrapping of obsolete product: The cost of disposing scrap. Scrap in support operations: Costs from defective items in indirect operations. Rework in internal support operations: Costs from correcting defective items in indirect operations. Downgrading: The cost difference between the normal selling price and the reduced price due to quality reasons. Variability of product characteristics: Rework losses that occur with conforming product (e.g.,overfill of packages due to variability of filling and measuring equipment). Unplanned downtime of equipment: Loss of capacity of equipment due to failures. Inventory shrinkage: Loss costs due to the difference between actual and recorded inventory quantity. Non-value-added activities: Cost due to redundant operations, sorting inspections, and other non-value added activities. A value-added activity increases the usefulness of a product to the customer; a non-value-added activity does not. 2.External Failure Costs come from costs associated with defects that are found after the customer receives the product or service. These costs included lost opportunities for sales revenue. Lost sales revenue costs would disappear if there were no deficiencies. External Costs Classifications Warranty charges: The costs involved in replacing or making repairs to products that are still within the warranty period. Complaint adjustment: The costs of investigation and adjustment of justified complaints from the defective product or installation. Returned material: The dollars associated with the receipt and replacement of defective product received from the field. Allowances: The costs of concessions made to customers due to substandard products accepted by the customer. Customer chose to use the product as is. Penalties due to poor quality: This can apply to goods or services delivered late or too early. Rework on support operations: Correcting errors on billing and other external processes. Revenue losses in support operations: An example is the failure to collect receivables from some customers. Lost Opportunities for sales revenue: Profit margin on current revenue lost due to customers who switch for reasons of quality. This includes canceled contracts due to poor quality. Also includes lost of new customers 3.Prevention costs are one of the four elements of cost of quality. When implement and tracking a cost of quality system within a company, management typically focuses on internal and external failure costs. Management studies the costs due to defects and not the cost to prevent the defects. Costs of prevention focuses on the actions taken to prevent the creation of defects. Companies that pursue operation excellence track these costs and purposely alllocate money to this element. These companies spend more on prevention methods than the other quality cost elements. Here are examples of these costs: Quality planning: This includes the broad array of activities which collectively create the overall quality plan and the numerous specialized plans. It includes also the preparation of procedures needed to communicate these plans to all concerned. New-products review: This inlcudes design review, reliability engineering, risk assessment, FMEA, Design of Experiements and other quality-related activities associated with the launching of new design. Process planning: Process capability studies, inspection planning, and other activities associated with the manufacturing and service processes. Process control: In-process inspection and test to determine the status of the process (rather than for product acceptance). This includes SPC, Anova Studies and guardbanding. Quality audits: Evaluating the execution of activities in the overall quality plan. Read more on Quality Audits here. Supplier quality evaluation: Evaluating supplier quality activities prior to supplier selection, and auditing the activities during the contract Training: Preparing and conducting quality-related training programs. Conducting training on company procedures, specification and inspection activities. 4.Defect-detection techniques, like reviews or tests, are still the prevalent method to assure the quality of software. However, the economics behind those techniques are not fully understood. It is not always obvious when and for how long to use which technique. A cost model for defect-detection techniques is proposed that uses a reliability model and expert opinion for cost estimations and predictions. It is detailed enough to allow ?ne-grained estimates but also can be used with di?erent defect-detection techniques not only testing. An application of the model is shown using partly data from an industrial project. 2.1 Conformance Costs The conformance costs comprise all costs that need to be spent to build the software in a way that it conforms to its quality requirements. This can be further broken down to prevention and appraisal costs. Prevention costs are for example developer training, tool costs, or quality audits, i.e. costs for means to prevent the injection of faults. The appraisal costs are caused by performance of various types of tests and reviews. We added in Fig. 1 further detail to the PAF model by introducing the main types of concrete costs that are important for defect-detection techniques in our current cost model. Note that there are more types that could be included, for example, maintenance costs. The appraisal costs were detailed to the setup and execution costs. The former constituting all initial costs for buying test tools, con?guring the test environment, and so on. The latter means all the costs that are connected to actual test executions or review meetings, mainly personnel costs. 2.2 Nonconformance Costs The nonconformance costs come into play when the software does not conform to the quality requirements. These costs are divided into internal failure costs and external failure costs. The former contains costs caused by failures that occurred during development, the latter describes costs that result from failures at the client. On the nonconformance side, we have fault removal costs that can be attributed to the internal failure costs as well as the external failure costs. This is because if we found a fault and want to remove it, it would always result in costs no matter whether caused in an internal or external failure. Actually, there does not have to be a failure at all. Considering code inspections, faults are found and removed that have never caused a failure during testing. It is also a good example that the removal costs can be quite di?erent regarding di?erent techniques. When a test identi?es a failure, there needs to be considerable e?ort spent to ?nd the corresponding fault. During an inspection, faults are found directly. Fault removal costs also contain the costs for necessary re-testing and re-inspections. External failure also cause support costs. These are all costs connected to customer care, especially the e?ort from service workers identifying the problem. Finally, compensation costs could be part of the external failure costs, if the failure caused some kind of damage at the customer site. We might also include loss of sales because of bad reputation in the external failure costs but do not especially look at it in this paper because it is out of scope. 2.3 Period A further concept we need to introduce is that of a period. It denotes a speci?c time interval in the life cycle. It does not have to correspond to a classical waterfall phase and can be used with an iterative process as well. The point is only to be able to (1) estimate the fault removal costs depending on the point in time and (2) have a basis for the calculation of the present net values. The ?rst is important because the additional work increases the later the fault is removed. For example if a design fault is detected early only the design documents need to be changed, later also the code and test cases have to be adapted. This is also shown, for example, by Jones [6]. The latter is important because to be able to compare costs the cash ?ows need to be analysed in dependence of the point in time when they occur. We depict a typical change in nonconformance costs during time in Fig. 2. Time Operation Development and quality assurance Nonconformance costs Figure 2: Change of nonconformance costs per failure over time 3. COST MODEL The basis for the analysis of the quality costs is the net present value of the cash ?ows (NPVCF), i.e. the revenues and costs during the life cycle of the software that are related to quality. This metric is su?cient to judge the earning power and also to compare di?erent defect-detection techniques. For further analyses other metrics, such as return on investment (ROI) or SQPI can be used [16]. 3.1 Directly Measurable Costs In this ?rst part of the quality costs, we want to classify those costs that can be directly measured or at least be estimated accurately during the usage of the defect-detection technique. For a speci?c defect-detection technique we have ?xed initial investments called setup costs (csetup) that contain for example tool or workstation costs. We assume them to emerge at the start of development and therefore have already the net present value. Furthermore, we have the dynamic part of the appraisal costs, e.g. personnel for tests and inspections, that we call execution costs (cexec). Furthermore, the fault removal costs for faults that werefound during the defect-detection technique under consideration can be measured directly. We call this cremv(p) which denotes the fault removal costs at the period p. With this information we can determine the direct costs (cdirect) of the defect-detection technique by adding up the execution and fault removal costs for all periods where we have direct measurements and the setup costs. The periods that we look at here are typically the periods in which the defect-detection technique was used.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.