1
play

1 How To Measure Quality? Approaches to QA subjective Efficiency - PDF document

Feb 20, 2024 •394 likes •443 views

Contents Last Time Introduction Introduction Software Development Processes Software Development Processes Project Management Project Management Requirements Engineering Requirements Engineering Software

  1. Contents Last Time � Introduction Introduction � � Software Development Processes Software Development Processes � � Project Management Project Management � � Requirements Engineering Requirements Engineering � � Software Construction Software Construction � � Group processes Group processes � � Quality Assurance � What is Quality Assurance? � Testing (Lecture 7) � Planning Quality and Inspections (Lecture 8) � Software Management and Evolution 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Today - Quality Assurance What is Quality Assurance? QA is the combination of planned and unplanned � What is Quality Assurance? activities to ensure the fulfillment of predefined quality � What is Quality? standards. � Constructive vs. analytic approaches to QA � Qualitative vs. quantitative quality standards � Measurement � Derive qualitative factors from measurable quantitative factors � Software measures (metrics) 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Some Example Metrics Some Example Metrics (cont.) � To measure reliability � To measure efficiency � Time behaviour � MTTF (Mean Time To Failure) • Transactions per second � Availability • Response time � To measure robustness • Screen refresh time � Resource behaviour � Time to restart after a failure • KBytes of executables � Probability of data corruption on failure • LOC � To measure portability • Number of processors � Number of target systems � To measure usability � Percentage of target dependent statements � Training time � Number of help frames � Measurement is necessary 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 1

  2. How To Measure Quality? Approaches to QA subjective Efficiency Quality Factor � Constructive Approaches properties The usage of methods, languages, and tools that depends ensure the fulfillment of some quality factors. on � Syntax-directed editors Property/ Property/ Property/ Speed � Enforced coding guidelines Criteria Criteria Criteria Size � Type systems determined � Standards by � … Response time in s objective Metric Metric Metric LOC measurements ... 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Standards Standards (cont.) � How to follow them � Two types of standards � Involve the software engineers � Product � Review and modify regulary � Provide software tools to support standards � Process � It takes time to develop standards � Standards are important � Base organisational standars on national and international � Based on experience standards • ISO 9000, ... � A framework for implementing the quality � Documentation standards assurance process � Documentation process standards � Assist in continuity � Document standards � Document interchange standards 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Approaches to QA (cont.) Approaches to QA (cont.) � Software Process Improvement � Analytic approaches The usage of methods, languages, and tools to observe The improvement of development processes to yield the current quality level. better products � Inspections � Static analysis tools (e.g. lint) � Testing � ... 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 2

  3. Quality is ... And Quality is … Sponsor User � … I know it when I see it � … it suits the client/user Functionality Low costs � … it conforms to the specification Efficiency Easy to learn I ncreased productivity � … it has some inherent quality Easy to remember Short time of delivery � … it depends on the price Reliability Easy to use Flexibility � … it depends on the delivery date Few errors Readable code Good design Good documentation Maintainer/modifier 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU The Quality Triangle Quality Factors (ISO 9126) � Different goals for Suitability different projects and Accuracy Lead time Functionality Interoperability organizations (close delivery time) Security � Medical equipment Maturity Reliability Fault tolerance � ATM Recoverability � Text editor Understandability Usability Learnability Operability � ”Good Enough” Time behavior Efficiency Software Resource behavior Analyzability Changeability Maintainability � Quality must be Stability Functionality Quality Testability measured goal- (number of “features”) (absense of errors) Adaptability oriented Installability Portability Conformance 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Replaceability Error vs. Fault vs. Failure HP’s Fault Classification Fault origin: WHERE? Specification/ Environment/ Documen- Design Code Other requirements support tation ?! Fault type: WHAT? can lead to can lead to Requirements HW interface (Inter-)Process Logic Test HW or communications specifications SW interface Computation Test SW Data definition human error fault failure Functionality User interface Data handling Integration SW Module design � Different types of faults Functional Module Development description Logic interface/ tools description implementation � Different identification techniques � Different testing techniques Error checking Standards � Fault prevention and -detection strategies should Standards be based on expected fault profile � Individual differences Missing Unclear Wrong Changed Better way 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Fault mode: WHY? 3

  4. Fault Profile of a HP Division Improving Quality 6% 11% Data handling Resources Products Processes Documentation � Personnel � Code � Methods 19% Requirements Hardware � Tools � Design � Management 18% Process/ interprocess � Budget � Requirements � Accounting Logic � ... � ... � ... 5% Computation Other code 4% Ordinary 5% testing 32% Easy to measure See [Pfleeger 98]. 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU The Message Summary � What is Quality Assurance? Quality is relative � What is Quality? Quality covers more than just code Establish a quality culture 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU Next time � Introduction Introduction � � Software Development Processes Software Development Processes � � Project Management Project Management � � Requirements Engineering Requirements Engineering � � Software Construction Software Construction � � Group processes Group processes � � Quality Assurance � What is Quality Assurance? What is Quality Assurance? � � Testing (Lecture 7) � Planning Quality and Inspections (Lecture 8) � Software Management and Evolution 12/9 - 08 Programvarukonstruktion - Jonny Pettersson, UmU 4

Recommend

More recommend