1. 1Software Measurement Advanced Software Engineering COM360 University of Sunderland © 2001

2. Where does Software Measurement fit in? Look at software measurement from the perspective of software quality assurance….. SQA REVIEWS TESTING MEASURE- MENT STANDARDS& PROCEDURES

3. 2Software Measurement Software Measurement is... ‘ the objective assignment of numbers or symbols to attributes of a software process or product in such a way as to describe them according to clearly defined rules...’

4. 3Software Measurement Why should we measure? 4what are our goals? 4what information is required? 4what can we collect? 4How do we act upon the data?

5. 4Software Measurement DON’T! Don’t define what you won’t collect.. Don’t collect what you won’t analyse.. Don’t analyse what you won’t use..

6. 5Software Measurement Goal / Question / Metric Goal - achieve a 10-fold improvement in post-release defects Question - how many existing faults? how effective are inspection techniques? How effective are tests? Metric - no. & type of faults, no. of defects found, % paths tested, complexity of code

7. 6Software Measurement What can be measured? Product examples… Spec. - size, functionality, maintainability. Design - size, modularity, coupling, cohesion Code - size, modularity, reliability, algorithmic complexity, maintainability Test - coverage, complexity, size

8. 7Software Measurement What can be measured? Process examples… Spec. - time, effort, changes, stability Design - time, effort, no. of inspection faults Testing - time, effort, no. of failures,

9. 8Software Measurement Hard & Soft Data HARD - objective figures - no.of people on a project, duration of tasks, size of documentation, etc. SOFT - subjective - level of experience, balance of teams, etc.

10. 9Software Measurement Why the slow acceptance of measurement? 4Inconclusive validation studies 4no agreement over standard measurements 4insufficient tool support 4initial set-up expense 4general lack of quality management

11. 10Software Measurement Those ‘well-defined rules’.. Nominal - names / categories Ordinal - ‘cold, warm, hot’ ‘small, med, large’ Interval - temperature ‘20 o C, 40 o C’ - scale Ratio - absolute temperature ‘20 o K, 40 o K’, time Absolute - counting no. of occurrences

12. 11Software Measurement Analysis.. Nominal - equivalence Ordinal - as above + greater than Interval - as above + ratio of any intervals Ratio - as above + ratio of any 2 scale values Absolute - as above + geometric mean, coeff. of variation

13. Function Points & Cyclomatic Complexity Function Points: Measure of functionality for ‘size’ - no. of external inputs -no. of external outputs -no. of enquiries -no. of files -no. external interfaces Cyclomatic Complexity: Module complexity based on a ‘graph’ of the module - nodes - predicate nodes

14. 13Software Measurement Measurement and the CMM