web usability and the new iso quality model
TRANSCRIPT
Web Usability and the New ISO Quality Model
©2001 Serco Ltd. 1© Nigel Bevan. Reproduction permitted provided the source is acknowledged
Nigel Bevan
Professional Usability Services
Topics
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My experiences with web quality as a member of the public …
Extensions to the ISO/IEC 9126 quality model
Applying the new ISO/IEC 9126 model to the web
London to Nancy?
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Getting a train to Nancy?
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CDG Airport
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(In the end, I decided to travel by Eurostar train from London)
Could ISO/IEC 9126 help?
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when designing a web site …
when evaluating a web site …
ISO/IEC 9126 Software Product Quality Model (1991)
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functionality reliability
usability efficiency
accuracysuitability
interoperabilitysecurity
understandabilitylearnabilityoperability
maturityfault tolerancerecoverability
availability
time behaviourresourceutilisationmaintainability portability
adaptabilityinstallabilityco-existencereplaceability
analysabilitychangeability
stabilitytestability
ISO 9241-11 Guidance on Usability (1998)
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Usability The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use
Effectiveness : The accuracy and completeness with which users achieve specified goals.
Efficiency : The resources expended in relation to the accuracy and completeness with which users achieve goals.
Satisfaction : The comfort and acceptability of use
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ISO/IEC 9126-1 (1999) Software Product Quality Model
quality in use
functionality reliability
usability efficiency
accuracysuitability
interoperabilitysecurity
understandabilitylearnabilityoperability
attractiveness
maturityfault tolerancerecoverability
availability
time behaviourresourceutilisation
maintainability portabilityanalysabilitychangeability
stabilitytestability
adaptabilityinstallabilityco-existencereplaceability
Potential changes in ISO/IEC 25010
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Software Operationcharacteristics
System Quality in Use
Software Support characteristics
Functionality
Security
Interoperability
Reliability
Operability
Efficiency
System Effectiveness
System Resources
Adverse Consequences
Stakeholder satisfaction
Maintainability
Portability
Revised definition of quality in use
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The extent to which a product meets a stakeholder’s needs to achieve specific goals with effectiveness, efficiency and satisfaction without adverse consequences in specific contexts of use
Stakeholder views of quality in use
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Stakeholder: End UserUsability
Usage OrganisationCost-effectiveness
Technical supportMaintenance
Goals:Characteristics
Personal goals Task goals Support goals
System effectiveness
User effectiveness Task effectiveness Support effectiveness
System resources Productivity (time) Cost efficiency (money)
Support cost
Adverse consequences
Risk to operator (health and safety)
Commercial risk Software failure or corruption
Stakeholder satisfaction
User satisfaction Management satisfaction
Support satisfaction
Quality in use in different contexts of use
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Adaptability
Learnability in useThe quality in use of the learning process
Flexibility in useThe capability of the product to provide quality in use in the widest range of contexts of use
Accessibility in useThe capability of the product to provide quality in use for people with the widest range of capabilities
Quality models
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SoftwareQuality Model
ComputerHardware
Non-targetSoftware
TargetSoftware
TargetData
Non-targetData
Computer System
Information System
Outer System (Business system, government system, embedded system)
CommunicationSystem
Data Quality Model
MechanicalSystems
HumanProcesses
Quality in UseModel
ISO/IEC 25012 data quality characteristics
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Characterstic Inherent ExternalAccuracy xCompleteness xConsistency xCredibility xCurrentness xAccessibility x xCompliance x xConfidentiality x xPerformance x xPrecision x xTraceability x xUnderstandability x xAvailability xPortability xRecoverability x
Inherent data quality characteristics
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Accuracy: the extent to which data has attributes that correctly represent the true value of the intended attribute of a concept or event in a specific context of useCompleteness: the extent to which subject data associated with an entity have values for all expected attributes and related entity instances in a specific context of useConsistency: the extent to which data has attributes that are free from contradiction and coherent with other data in a specific context of use.Credibility: the extent to which data has attributes that are regarded as true and believable by users in a specific context of useCurrentness: the extent to which data has attributes that are of the right age in a specific context of use
Inherent & external data quality characteristics
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Accessibility: the extent to which data has attributes that enable it to be reached in a specific context of use, particularly by people who need supporting technology or special configuration because of some disabilityCompliance: the extent to which data has attributes that adhere to standards, conventions or regulations in force and similar rules relating to data quality in a specific context of useConfidentiality: the extent to which data has attributes that ensure that it isaccessed and interpreted only by authorized users in a specific context of usePerformance: the extent to which data has attributes that can be processed and provide the expected levels of performance by using the appropriate amounts and types of resources under stated conditions and in a specific context of usePrecision: the extent to which data has attributes that are exact or that provide discrimination in a specific context of useTraceability: the extent to which data has attributes that provide an audit trail of accesses to the data and of any changes made to the data in a specific context of useUnderstandability: the extent to which data (and associated metadata) has attributes that enable it to be read and easily interpreted by users, and are expressed in appropriate languages, symbols and units in a specific context of use
External data quality characteristics
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Availability: the extent to which data has attributes that enable it to be retrieved by authorized users in a specific context of usePortability: the extent to which data has attributes that enable it to be moved from one platform to another preserving the existing quality in a specific context of use; this includes also the possibility to install and replace data in the destination platform.Recoverability: the extent to which data has attributes that enable the data to maintain and preserve a specified level of operations and quality, even in the event of failure, in a specific context of use
Examples of relationships between qualities
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S D Internal/ Inherent
Exter-nal
In use
S x x Consistency D x x
S x x Accuracy D x x x
S x x Portability D x x
Operability S x x x Precision D x x x
Quality in use Effectiveness Resources Consequences Satisfaction
Extend satisfaction to incorporate user experience
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Pragmatic user goalsAcceptable perceived experience of use (pragmatic aspects including efficiency)Acceptable perceived results of use (including effectiveness)Acceptable perceived consequences of use (including safety)
Hedonic goals (Hassenzahl)Pleasurable emotional reactions to the productStimulation (i.e. personal growth, an increase of knowledge and skills)Identification (i.e. self-expression, interaction with relevant others)Evocation (i.e. self-maintenance, memories)
Implications for SNCF web site
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Internal quality characteristicsShould follow established web guidelines
Quality in UseUser testing
Adaptability in different contextsFlexibility in Use: English
Data (station names)Completeness, Consistency, Credibility, Currentness, Understandability
StakeholdersUsers: may not be effective, efficient or satisfiedOrganisation: cost efficientSupport: missing data in the English database
Organisational satisfactionThe organisation is satisfied because there is no competition!
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www.usability.gov/pdfsFree download$35 book
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Questions?