C40 L12interfacenotes

							CSCC40            Analysis and Design of Information Systems                   user interface design
                  University of Toronto at Scarborough                                                     pg 1/2




Why is user interface design important?
        most business applications consists of 40-60% interface management
        interfaces are becoming more complex (3-D, virtual reality…)
        good design:
        reduces input and usage errors
        lowers the cost of system support
        makes users more productive



Why are user interfaces so poor?
        inadequate training of people developing user interfaces
        diversity of knowledge required to design good interfaces
        rapid technological advances making programming difficult
        poor communications between users, analysts and programmers
        unwillingness to pay for expertise or field testing, so programmers are left to design screens
        software engineers’ ignorance of usability and how to measure it



The impact of bad interface design can be measured in dollars.
For an employer, the cost of an employee is approximately double his or her salary. So an average annual
cost may be $100,000. For an 8-hour day and 250 working days per year, this translates to $50/hour
($0.83/minute or $0.0138/second) per employee.
                            100 screens/day * 10 sec. wasted/screen            $3,450/year per user
            60 unnecessary menu selections/day * 2 sec./selection                $414/year per user
 2 new application to learn/year * 2 extra training days/application           $1,600/year per user
                      50 preventable errors/year * 15 minutes/error              $625/year per user
                                                                             $6,089/year per user
With 20 users, the cost per year is over $100,000/year. That’s one employee.



What must we know about users?
          Some basic human characteristics:                      So, we should build interfaces that:
     we are more likely to learn by copying or asking
                                                                  allow people to learn by using them
                     than by reading
        we all build our own models of the world
                                                                        suggest correct models
                and what is should be like
                      learning is hard                                   rely on prior learning




What are the characteristics or a well-designed interface?

affordances
makes operation visible
design itself describes what the user can do with it
                   good example – the garbage can icon
                   poor example – the floppy disk icon for my laptop (it has no floppy drive)
CSCC40             Analysis and Design of Information Systems                   user interface design
                   University of Toronto at Scarborough                                                       pg 2/2




mapping functions
the design in some way shows a mapping between the intended us for the tool and the action of the
underlying technology
         good example – presentation of the font to be selected in the form/shape of the font
         poor example – function keys in general since their sequence is arbitrary
mental models
the underlying understanding that a person has about how a technology or a device works so that the user
has some idea that if they perform action A, then event B will follow
         good example – WYSIWYG what you see if what you get
         poor example – extra functions on a telephone
forcing functions
the design that prevent users from taking action which are inappropriate or which could lead to error
         good example – graying out non-applicable selections in a menu
         poor example – Unix allows every command as long as it’s typed correctly
feedback
a response is given to users indicating that an action is completed or in error
         good example – reverse video for selected icons
         poor example – Latex and other text formatting systems
automatic learning
a design that forces learning on the user by offering repetitive patterns of user action or screen displays
         good example – consistent placement of menu items and icons (MS Windows)
         poor example – a confirmation action that always requires a carriage return

dialogue modes

menu selection     – user selects one option from a list
instruction sets   – user enters commands
question/answer    – user responds to choices until desired action is reached
graphic-based      – combination or options, commands, icons, etc.


steps in designing user interfaces
plan
       identify what needs to be learned
       do highest risk items first
       identify users tasks to be performed through the interface
       select the most appropriate mode(s)
prototype
     prototype the entire dialogue (paper mockups and/or “active” screens)
     identifying all action and feedback
measure
     have several users work with the prototype
     measure the time they take
     map the actions they take
learn
     get feedback from users
     evaluate the measurements and mapping and look for improvement
go back to first step if improvements can be made