1 Chapter 3 1.Quality Management, 2.Software Cost Estimation 3.Process Improvement

 Process and product quality  Quality assurance and standards  Quality control 2 Software Engineering Application Development----> Chapter 3 Quality Management

Software quality management  Concerned with ensuring that the required level of quality is achieved in a software product.  Involves defining appropriate quality standards and procedures and ensuring that these are followed.  Should aim to develop a ‘quality culture’ where quality is seen as everyone’s responsibility. 3 Software Engineering Application Development----> Chapter 3

What is quality?  Quality, means that a product should meet its specification.  Some quality requirements are difficult to specify in an unambiguous way  Software specifications are usually incomplete and often unpredictable. 4 Software Engineering Application Development----> Chapter 3

Quality management activities  Quality assurance  Establish organisational procedures and standards for quality.  Quality planning  Select applicable procedures and standards for a particular project and modify these as required.  Quality control  Ensure that procedures and standards are followed by the software development team.  Quality management  should be separate from project management to ensure independence. 5 Software Engineering Application Development----> Chapter 3

Standards are the key to effective quality management. They may be international, national, organizational or project standards. Product standards Product standards define characteristics that all components should exhibit. e.g. a common programming style. Process standards Process standards define how the software process should be Performed. Quality Assurance and Standards 6 Software Engineering Application Development----> Chapter 3

Product and Process Standards 7 Software Engineering Application Development----> Chapter 3

 Encapsulation of best practice- avoids repetition of past mistakes.  They are a framework for quality assurance processes - they involve checking compliance to standards.  They provide continuity - new staff can understand the organisation by understanding the standards that are used. Importance of standards 8 Software Engineering Application Development----> Chapter 3

Software Quality Attributes 9 Software Engineering Application Development----> Chapter 3

Quality control This involves checking the software development process to ensure that procedures and standards are being followed. There are two approaches to quality control – Quality reviews; – Automated software assessment and software measurement. 10 Software Engineering Application Development----> Chapter 3

Quality reviews This is the principal method of validating the quality of a process or of a product. A group examines part or all of a process or system and its documentation to find potential problems. There are different types of review with different objectives – Inspections for defect removal – Reviews for progress assessment – Quality reviews (product and standards). 11 Software Engineering Application Development----> Chapter 3

Software Measurement and Metrics Software measurement is concerned with deriving a numeric value for an attribute of a software product or process. Measure Measure - quantitative indication of amount, dimension, capacity, or size of some attribute of a product or process. Metric Metric - quantitative measure of degree to which a system, component or process holds a given attribute. “A handle or guess about a given attribute.” 12 Software Engineering Application Development----> Chapter 3

Software Measurement and Metrics Why Measure Software? – To determine the quality of the current product or process – To predict qualities of a product/process – To improve quality of a product/process

Software Engineering Application Development----> Chapter Quality Management, 2.Software Cost Estimation 3.Process Improvement

15 Budget - To know what you will spend Controls - A lever to control the project Differential analysis - Monitor progress by comparing planned with estimated costs Cost database - Make future estimation better Marry costing to management - Cost estimation and planning/scheduling are closely related activities Software Engineering Application Development----> Chapter 3 Software Cost Estimation

16 Estimation Techniques 1.Expert judgment 2.Estimation by analogy 3.Pricing to win 4.Top-down estimation 5.Bottom-up estimation 6.Algorithmic cost modeling Software Engineering Application Development----> Chapter 3

17 predict software costs One or more experts in both software development and the application domain use their experience to predict software costs. Process iterates until an agreement is reached. Advantages: Relatively cheap estimation method. Can be accurate if experts have direct experience of similar systems Disadvantages: May be very costly (1) - Expert judgement Software Engineering Application Development----> Chapter 3

18 The cost of a project is computed by comparing the project to a similar project in the same application domain. Advantages: Accurate if project data available Disadvantages: Impossible if no comparable project has been tackled. Needs systematically maintained cost database. Estimation by analogy Software Engineering Application Development----> Chapter 3

19 The project costs whatever the customer has to spend on it. Advantages: You get the contract. Disadvantages: The probability that the customer gets the system he/she wants is small. Costs do not accurately reflect the work required Pricing to win Software Engineering Application Development----> Chapter 3

20 system level Start at system level and work out how the system functionality is provided. without Usable without knowledge of the system architecture and the components that might be part of the system. integration, configuration management and documentation Takes into account costs such as integration, configuration management and documentation underestimate Can underestimate the cost of solving difficult low-level technical problems. Top-down estimation Software Engineering Application Development----> Chapter 3

21 Start at the lowest system level. The cost of each component is estimated individually. These costs are added to give final cost estimate. designed in detail Accurate method if the system has been designed in detail. May underestimate costs of system level activities such as integration and documentation. Bottom-up estimation Software Engineering Application Development----> Chapter 3

22 – Each method has strengths and weaknesses. Therefore, estimation should be based on several methods – If these do not return approximately the same result, there is insufficient information available – Pricing to win is sometimes the only applicable method Estimation methods Software Engineering Application Development----> Chapter 3

23 Cost is estimated as a mathematical function of product, project and process attributes whose values are estimated by project managers. Most commonly used product attribute for cost estimation Most models are basically similar but with different attribute values Algorithmic cost modelling Software Engineering Application Development----> Chapter 3

24 1.Quality Management, 2.Software Cost Estimation 3.Process Improvement

25 Software Engineering Application Development----> Chapter 3 Process Improvement Understanding, Modelling and Improving the Software Process Process and product quality Process analysis and modelling Process measurement Process classification

The Process Improvement Cycle 26 Software Engineering Application Development----> Chapter 3

Understanding existing processes Introducing process changes to achieve organisational objectives which are usually focused on quality improvement, cost reduction and schedule acceleration Most process improvement work so far has focused on defect reduction. This reflects the increasing attention paid by industry to quality However, other process attributes can be the focus of improvement Process Improvement 27 Software Engineering Application Development----> Chapter 3

Process attributes 28 Software Engineering Application Development----> Chapter 3

Process analysis – Model and analyse (quantitatively if possible) existing processes Improvement identification – Identify quality, cost or schedule bottlenecks Process change introduction – Modify the process to remove identified bottlenecks Process change training – Train staff involved in new process proposals Change tuning – Evolve and improve process improvements Process improvement stages 29 Software Engineering Application Development----> Chapter 3

Process quality and product quality are closely related A good process is usually required to produce a good product For manufactured goods, process is the principal quality determinant Process and product quality 30 Software Engineering Application Development----> Chapter 3

31 Software Engineering Application Development----> Chapter 3 Process Improvement Process and product quality Process analysis and modelling Process measurement Process classification

Process analysis and modelling Process analysis – The study of existing processes to understand the relationships between parts of the process and to compare them with other processes Process modelling – The documentation of a process which records the tasks, the roles and the entities used – Process models may be presented from different perspectives (examples ?) 32 Software Engineering Application Development----> Chapter 3

Questionnaires and interviews – Must be carefully designed. Participants may tell you what they think you want to hear Ethnographic analysis – Involves assimilating process knowledge by observation Process analysis techniques 33 Software Engineering Application Development----> Chapter 3

34 Software Engineering Application Development----> Chapter 3 Process Improvement Process and product quality Process analysis and modelling Process measurement Process classification

Wherever possible, quantitative process data should be collected – However, where organisations do not have clearly defined process standards this is very difficult as you don’t know what to measure. A process may have to be defined before any measurement is possible Process measurements should be used to assess process improvements – But this does not mean that measurements should drive the improvements. The improvement driver should be the organizational objectives Process measurement 35 Software Engineering Application Development----> Chapter 3

36 Software Engineering Application Development----> Chapter 3 Process Improvement Process and product quality Process analysis and modelling Process measurement Process classification

Informal – No detailed process model. Development team chose their own way of working. Works with prototypes & short lifetime products Managed – Defined process model which drives the development process. Works with large systems & long lifetime products Methodical – Defined development methods supported by CASE tools Improving – improvements considered and introduction procedures Process classification 37 Software Engineering Application Development----> Chapter 3

Process used should depend on type of product which is being developed – For large systems, management is usually the principal problem so you need a strictly managed process. For smaller systems, more informality is possible. There is no uniformly applicable process which should be standardised within an organisation – High costs may be incurred if you force an inappropriate process on a development team Process choice 38 Software Engineering Application Development----> Chapter 3

Thank you Software Engineering Application Development----> Chapter 3 39