Measurement What is it and why do it? 2/23/2019 SWEN 5430 Software Metrics

Measurement in every day life Measurement is the process by which numbers or symbols are assigned to attributes of entities in the real world in such a way as to describe them according to clearly defined rules. 2/23/2019 SWEN 5430 Software Metrics

Measurement in every day life (continued) Measurement captures information about attributes of entities. Entity is an object or an event in the real world Attribute is a feature or property of an entity Measurement is a process whose definition is far form clear cut Measurement has different interpretations 2/23/2019 SWEN 5430 Software Metrics

Measurement in every day life (continued) “What is not measurable make measurable” Galileo Galilei (1564-1642) Two kinds of quantification Measurement and Calculation Measurement is a direct quantification Calculation is an indirect quantification Use direct and indirect to distinguish Measurement from Calculation 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering Software Engineering describes the collection of techniques that apply an engineering approach to the construction and support of software products Managing costing planning Modeling analyzing specifying Designing implementing Testing maintaining 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Neglect of measurement in SWEN Engineering uses methods based on models and theories. Once a Scientific method suggests the validity of a model or theory scientists uses measurement to apply the theory to practice 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Neglect of measurement in SWEN For most SW development projects engineers Fail to set measurable targets for SW projects. Fail to understand and quantify the component costs. Don’t quantify or predict the quality of the products. Allow untested methodology to try another newly developed technology. 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Gilb’s Principle of Fuzzy Targets: “Projects without clear goals will not achieve their goals clearly.” 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Objectives for SW Measurement “you cannot control what you cannot measure” (DeMarco, 1982) How can a manager or an engineer tell if the project is succeeding if they have no measure of it’s success? The managers & engineer must control and run the projects. 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Objectives for SW Measurement Manager prospective What does the process cost? How productive is the staff? How good is the code being developed Will the user be satisfied with the product How can the process be improved 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Objectives for SW Measurement Engineers prospective Are the requirements testable? Have we found all the faults? Have we met our product, process and resource (PPR ) goals? Can we measure attributes of this PPR to make predictions for future? 2/23/2019 SWEN 5430 Software Metrics

Measurement in Software Engineering (continued) Measurement for understanding, control and improvement Measures help to understand what is happening during development and maintenance Measurement allows the control of the PPR Measurement encourages the improvement of the PPR 2/23/2019 SWEN 5430 Software Metrics

The scope of software metrics Software metrics activities involves many methods of software measurement collection processes. Cost and effort estimation Productivity measures and models Data Collection Quality models and measures Reliability models 2/23/2019 SWEN 5430 Software Metrics

The scope of software metrics (continued) Software metrics activities involves many methods of software measurement collection processes. Performance evaluation and models Structural and complexity metrics Capability-maturity assessment Management by metrics Evaluation of methods and tools 2/23/2019 SWEN 5430 Software Metrics

Summary Measurement is essential for good Software Engineering Practices. Other engineering disciplines suggest that measurement must play a role in SWEN. SW measurement is a diverse collection of fringe topics (SW metrics) that range from models for predicting SW project costs at the specific stages of the SW life cycle. 2/23/2019 SWEN 5430 Software Metrics

Summary (continued) Measurement is essential for good Software Engineering Practices. SW metrics engineering probably lacks the rigor applies to other engineering disciplines. Managers & Engineers must have specific, clearly stated objectives for measurement. Must research and apply new measurement methodology for attributes of interest. 2/23/2019 SWEN 5430 Software Metrics