Usability and Security

More documents

Recommendations

Info

• Nielsen (1993) points out that usability is a quality attribute that assesses how easy user interfacesare to use. The word "usability" also refers to methods for improving ease-of-use during the designprocess. According to Nielsen, usability is defined by five quality components: learnability,efficiency, memorability, errors, and satisfaction 2 ;• Shackel (1991) reports that the definition of usability was probably first attempted by Miller (1971)in terms of measures for “ease of use”. The concept of usability was first fully discussed and adetailed formal definition was attempted by Shackel (1981) in which he defines usability as: thecapability in human functional terms to be used easily and effectively by the specified range ofusers, given specified training and user support, to fulfill the specified range of tasks, within thespecified range of tasks, within the specified range of environmental scenarios 3 ;• Booth (1989) outlines that usability has four factors: usefulness, effectiveness (ease of use),learnability, and attitude (likeability) 4 ;• Brinck, Gergle, and Wood (2002) share a similar perspective that usability is: functionally correct,efficient to use, easy to learn, easy to remember, error tolerant, and subjectively pleasing 5 ;• Hix and Hartson (1993) classify usability into initial performance, long-term performance,learnability, retainability, advanced feature usage, first impression and long-term user satisfaction 6 ;• In addition to those views mentioned above, Gould (1988) defines usability into more components,including system performance (reliability, responsiveness), system functions, user interface, readingmaterials, language translation, outreach program, ability for customers to modify and extend,installation, field maintenance and service-ability, advertising, and support group users 7 .2.1.2 Definition usedAs mentioned in the previous paragraph, the term usability is used broadly and is defined in differentways. We have seen that authors/ organizations in the usability community have different opinions andperceptions on what they consider to be a useful attribute/ aspect or as some of them call it components.We are able to conclude that there is clearly an overlap between the various definitions. Some attributeshave the same meaning, but are described using other words, e.g. “satisfaction” with “long-term usersatisfaction” and “efficiency” with “efficient to use”. Furthermore we noticed that “efficiency” is also oneof the quality aspects as defined by NOREA. For our thesis we will use the definition as defined by ISO,which besides from being a standard that is adopted by an international standardizing/standardsorganization, it suits the purpose of the research question in this thesis.Effectiveness, efficiency and satisfaction can be specified for different goals 1 :Usability objective Effectiveness measures Efficiency measures Satisfaction measuresOverall usability Percentage of goals achieved Time to complete a task Rating scale for satisfactionPercentage of users successful completing task Tasks completed per unit time Frequency of discretionary useAverage accuracy of complete tasks Monetary cost of performing the task Frequency of complaintsTable 1: Examples of measures of usability4
2.1.3 Usability componentsIn order to specify or measure usability it is necessary to identify the goals and to decomposeeffectiveness, efficiency and satisfaction and the components of the context of use into sub-componentswith measurable and verifiable attributes. The framework on the next page illustrates the components ofusability and the relationship between them 1 .Figure 1: Usability frameworkWhen specifying or measuring usability the following information is needed:• a description of the intended goals: this includes the criteria that would satisfy the intended goals;• a description of the components of the context of use including users, tasks, equipment, andenvironments: this may be a description of an existing context, or a specification of intendedcontexts;• target or actual values of effectiveness, efficiency, and satisfaction for the intended contexts:measures of effectiveness relate the goals of the user to the accuracy and completeness with whichthese goals can be achieved, measures of efficiency relate the level of effectiveness achieved to theexpenditure of resources and measures of satisfaction relate the extent to which users are free fromdiscomfort and their attitudes towards the use of the product.2.2 What is security?When we talk about security in this thesis, we refer to information security. Information is an asset that,like other important business assets, is essential to an organization’s business and consequently needs tobe suitably protected. Defining, achieving, maintaining, and improving information security is essential tomaintain competitive edge, cash flow, profitability, legal compliance, and commercial image.5
Page 1 and 2: Usability and SecurityUniversity: V
Page 3 and 4: ACKNOWLEDGMENTSThis thesis covers t
Page 5 and 6: IntroductionThe developments in Inf
Page 7: idging the gap between theory and p
Page 11 and 12: custom approach 12 . An example of
Page 13: put usability and security amongst
Page 16 and 17: Security aspects:• Confidentialit
Page 18 and 19: ambiguous. Controlled answers offer
Page 20 and 21: 3.3.3 TokensIn this paragraph the t
Page 22 and 23: Security aspects:• Confidentialit
Page 24 and 25: The strengths, weaknesses and usabi
Page 26 and 27: conclude that the most efficient bi
Page 28 and 29: e guessed, which results in a low s
Page 30 and 31: To answer our main research questio
Page 32 and 33: AppendixInterview with Martin Wijnm
Page 34 and 35: Sources1 ISO 9241-11, Part 11: Guid

Usability and Security

Create successful ePaper yourself

Delete template?

Save as template?