====== 4.3.6 Usability ====== [[dido:public:ra:1.4_req:2_nonfunc| Return to Non-Functional Requirements]] ===== About ===== [[dido:public:ra:xapend:xapend.a_glossary:u:usability]] is defined by [[dido:public:ra:xapend:xapend.b_stds:tech:iso:square_sys_model]] as the degree to which a product or system can be used by [[dido:public:ra:xapend:xapend.a_glossary:s:stakeholder]] (i.e., specified users) to achieve specified [[dido:public:ra:xapend:xapend.a_glossary:g:goal | goals]] within a specified context. ==== Goals ==== The goals of usability are(( Justin Mifsud, __Usability Metrics – A Guide To Quantify The Usability Of Any System__, Accessed 18 November 2020, [[https://usabilitygeek.com/usability-metrics-a-guide-to-quantify-system-usability/]] )): - **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. ==== Sub-Characteristics ==== This characteristic is composed of the following sub-characteristics(( [[dido:public:ra:xapend:xapend.a_glossary:i:iso]], __Usability__, ISO25000, Accessed: 17 November 2020, [[https://iso25000.com/index.php/en/iso-25000-standards/iso-25010/61-usability]] )): * //**[[dido:public:ra:xapend:xapend.a_glossary:a:appropriateness_recognizability]]** - Degree to which users can recognize whether a product or system is appropriate for their needs.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] * //**[[dido:public:ra:xapend:xapend.a_glossary:l:learnability]]** - Degree to which a product or system can be used by specified users to achieve specified goals of learning to use the product or system with effectiveness, efficiency, freedom from risk and satisfaction in a specified context of use.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] * //**[[dido:public:ra:xapend:xapend.a_glossary:o:operability]]** - Degree to which a product or system has attributes that make it easy to operate and control.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] * //**[[dido:public:ra:xapend:xapend.a_glossary:u:uerror_protection]]** - Degree to which a system protects users against making errors.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] * //**[[dido:public:ra:xapend:xapend.a_glossary:u:interface_aesthetics]]** - Degree to which a user [[dido:public:ra:xapend:xapend.a_glossary:i:interface|interface]] enables pleasing and satisfying interaction for the user.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] * //**[[dido:public:ra:xapend:xapend.a_glossary:a:accessibility]]** - Degree to which a product or system can be used by people with the widest range of characteristics and capabilities to achieve a specified goal in a specified context of use.//[[dido:public:ra:1.4_req:2_nonfunc:30_usability#fn__1| (1)]] See: * [[dido:public:ra:xapend:xapend.b_stds:tech:iso:square_sys_model]] * [[https://iso25000.com/index.php/en/iso-25000-standards/iso-25010/61-usability]] * [[dido:public:ra:xapend:xapend.b_stds:tech:iso:ergonomics]] ==== Metrics ==== [[dido:public:ra:1.4_req:2_nonfunc:30_usability| Return to the Top]] Usability as a characteristic is often considered a subjective quality and left to "interpretation", however, there are metrics which use to quantify these sub-characteristics. Before we delve into the definition of the specific metrics, it is important to understand why we need metrics rather than just rely on intuitive evaluations. A core reason to collect Usability Metrics is to provide data about a stakeholder's understanding of a product's usability rather than the developer's understanding of usability. When the two understandings (i.e., interpretations) converge everyone is happy resulting in a way forward. That result may be to either continue in the same direction or to have a reassessment of the user's needs. The metrics must quantify that the system meets the [[dido:public:ra:1.4_req:2_nonfunc:30_usability#goals| goals]] of the overall system: - The [[dido:public:ra:1.4_req:2_nonfunc:30_usability#effectiveness_metrics| Effectiveness Metrics ]] of the communication between the system and the users - The [[dido:public:ra:1.4_req:2_nonfunc:30_usability#efficiency_metrics| Efficiency Metrics]] of the users use of the system to accomplish their work - The [[dido:public:ra:1.4_req:2_nonfunc:30_usability#satisfaction_metrics| Satisfaction Metrics]] of the users that the [[dido:public:ra:1.4_req:2_nonfunc:30_usability#sub-characteristics| sub-characteristics]] of the system are met. Ultimately, the primary objective of usability metrics for evaluating a system or product is properly engineered (i.e., neither under- or over-engineered). * [[dido:public:ra:1.4_req:2_nonfunc:30_usability:effectiveness]] * [[dido:public:ra:1.4_req:2_nonfunc:30_usability:efficiency]] * [[dido:public:ra:1.4_req:2_nonfunc:30_usability:satisfaction]] ===== DIDO Specifics ===== [[dido:public:ra:1.4_req:2_nonfunc:30_usability| Return to the Top]] : To be added/expanded in future revisions of the DIDO RA /**=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- /* To add a discussion page to this page, comment out the line that says ~~DISCUSSION:off~~ */ ~~DISCUSSION:on|Outstanding Issues~~ ~~DISCUSSION:off~~