1 Product Desirability Social Acceptability Practical Acceptability

2 Social Acceptability Social norms applicable at the time –Bermuda shorts and stonewashed jeans –KBC and Packman –Pokemon –Auto-rickshaw as a family vehicle –Non-branded products –E-invitation for a wedding

3 Practical Acceptability Cost Usefulness Compatibility Reliability Support etc.

4 Usefulness Utility Usability

5 Usefulness Utility –Can the functionality of the product in principle do what it is supposed to do –Does an educational product teach? –Does an entertainment product entertain? –Does a communications product communicate?

6 Usefulness Usability –The extent to which a targeted user can effectively utilize the functionality –Applies to all aspects of a system with which a human might interface

7 Desirable Socially Acceptable Utility Usable Otherwise Practically Acceptable

8 Game

9 Clues 1.Is equipped with an internal combustion engine - pass 2.Is available in yellow, black, and yellow and black combo 3.Has three wheels - pass 4.Has a parking brake and a foot brake 5.Has a 3-speed forward and reverse gear box - pass 6.Levels uneven surfaces nicely and quickly 7.Blast weights can be added to level different types of surfaces - pass

10 Answer

11 Answer

12 Clues 1.Is equipped with an internal combustion engine 2.Is available in yellow, black, and yellow and black combo 3.Has three wheels 4.Has a parking brake and a foot brake 5.Has a 3-speed forward and reverse gear box 6.Levels uneven surfaces nicely and quickly 7.Blast weights can be added to level different types of surfaces

13

14 Categories of Usability Goals Learnability Ease of use Speed of use Error-free use Retention over time Subjective satisfaction

15 Learnability Learnability goals are the most fundamental usability goals

16 Learnability… Novice users –First-time usability of the product –“Tourists should be able to find out the number of the bus they need to take.” –“First year students should be able to register without help.” Advanced beginners / competent performers –Ease to learn more features –Ease to improve conceptual models –“Regular customers should learn to use the one-click feature.” – “Daily customers should be able to order vegetables on their cell phones.”

17 Learnability… First version –All users start out being novices –Have no knowledge of the product –“Recognize terms used in the interface.” Subsequent versions –Users will transfer existing knowledge –Users will have to learn the differences –“Be 100% backward compatible with these tasks…” –“Users should notice the new wizard.”

18 Example Questions How quickly can a novice user start using the product? How quickly can a novice user become an advanced beginner and an advanced beginner become a competent performer? How much of training and practice is necessary? Is the user encouraged to explore the product?

19 Example Learnability Goals?

20 Ease of Use Define tasks a given user must be able to do –“All advanced beginners should be able to find and replace text.” Define a preferred method of doing things –“All competent performers should be able to do a find operation on multiple documents with one command rather than opening each file separately.” Avoidable tasks –“Users need not write anything on the deposit envelope.”

21 Example Questions How many users can perform the tasks that they are supposed to? How many tasks do users need to do that are avoidable? How easy is it for a group of users to work together? How easily does the product fit in the users’ current conceptual model?

22 Example Ease of Use Goals?

23 Speed of Use Time taken –“It should take a farmer less than five minutes to identify a transporter.” Number of steps –“A novice user should be able to deposit cash at the ATM in 3 steps.” –“Regular commuters should be able to tell time to the next bus without clicking.” Same as ease of use?

24 Example Questions How long does it take for the user to carry out benchmark set of tasks? How many steps are involved in a routine task? How long does it take for users to recover from errors?

25 Example Speed of Use Goals?

26 Error-free Use Error –An action of the user that does not accomplish the desired goal Error Rate of a product –Number of errors made by users while performing benchmark tasks –Percentage of users who make an error while doing a task Severity of Errors –The more difficult it is to recover from the error, more sever it is

27 Error-free Use Limits for error rate of the product –“Should be able to identify himself without errors” Limits for severity of the errors (catastrophic, major, minor) –“It should be impossible for transporters to loose data.” –“Prevent users from entering more amount than they can withdraw.” Ability of users to recognize errors –“Error messages should not be confused with other messages.” Ability of users to recover from errors

28 Example Questions How many and what kind of errors are made by users to carry out benchmark tasks? How many errors do users make repeatedly? How long does it take for the users to identify the error condition? How forgiving is the interface? What percentage of errors can users recover from? How many users can identify the cause of the error and the method of recovering from errors? How long does it take for users to recover from errors?

29 Example Error-free Use Goals?

30 Retention Over Time Most advanced beginners are intermittent users Don’t have to learn the system from scratch They just need to remember how to use the system based on their previous experience Parts of the interface that are used intermittently –Installation programs –Backup –Restore

31 Retention Over Time… Retention is rarely tested –A product that is easy to learn is considered to be easy to retain –Define goals are for guiding design

32 Example Questions How much of the interface can a user recall after pre-determined amount of time (hours, days, months, years)? With how much effort and time can a user re- learn what he has forgotten?

33 Example Retention Goals?

34 Subjective Satisfaction Expectations of pleasantness –Derived from life goals and experience goals of users Significantly influence the desirability Important for non-work products –Home computing, games, fiction Important for niche markets –Hasselblad for photographers –Apple Mac for designers –Manual blood pressure meter for doctors

35 Example Questions How much did the users enjoy using the product? Is it “value for money” or is it “hassle free trip”? What are the cultural issues that matter? How do users rate the product over competition?

36 Example Satisfaction Goals?

37 Usability Goals Learnability Ease of use Error-free use Speed of use Retention over time Subjective satisfaction

38 Goal Driven Design Goals drive design –Help speed up design process –Make design activity tangible –Help evaluate design Set goals before design!!!

39 You Can’t Meet All Goals Life critical systems –Railway signals, ATC, operation theatre, water supply –Reliability, error free use, long training

40 You Can’t Meet All Goals Life critical systems Industrial and commercial uses –Banks, railway reservation, inventory –Speed of use, minimal training, operator fatigue and burnout

41 You Can’t Meet All Goals Life critical systems Industrial and commercial uses Home, office, public places –Office products, ATMs, cell phones –Some tasks with zero learning, encourage self learning and exploration, support wide range of users (A/NB/CP), subjective satisfaction

42 You Can’t Meet All Goals Life critical systems Industrial and commercial uses Home, office, public places Exploratory and creative –Architecture, graphic design, product design, audio studio, GIS / GPS / MIS –Ease of use, some training, encourage self learning and exploration

43 You Can’t Meet All Goals Life critical systems Industrial and commercial uses Home, office, public places Exploratory and creative Cooperative work –Chat, mailing lists, DLP –Some tasks with zero learning, ease of use, encourage self learning and exploration, support wide range of users (A/NB/CP), subjective satisfaction

44 You Can’t Meet All Goals Life critical systems Industrial and commercial uses Home, office, public places Exploratory and creative Cooperative work Micro interface –Hardware, Devnagari keyboard, new paradigm –Demonstrate new concept, attract early adaptors, zero learnability, ease of use

45 Universal Usability (cont.) Cultural and international diversity –Characters, numerals, special characters, and diacriticals –Left-to-right versus right-to-left versus vertical input and reading –Date and time formats –Numeric and currency formats –Weights and measures –Telephone numbers and addresses –Names and titles (Mr., Ms., Mme.) –Social-security, national identification, and passport numbers –Capitalization and punctuation –Sorting sequences –Icons, buttons, colors –Pluralization, grammar, spelling –Etiquette, policies, tone, formality, metaphors

46 Universal Usability (cont.) Users with disabilities –Designers must plan early to accommodate users with disabilities –Early planning is more cost efficient than adding on later –Businesses must comply with the "Americans With Disabilities" Act for some applications Elderly Users –Including the elderly is fairly ease, designers should allow for variability within their applications via settings for sound, color, brightness, font sizes, etc.

47 Goals for our profession Potential research topics –Reducing anxiety and fear of computer usage –Graceful Evolution –Specification and implementation of interaction –Direct manipulation –Input devices –Online assistance –Information exploration

48 Goals for our profession (cont.) Providing tools, techniques, and knowledge for system implementers –Rapid prototyping is easy when using contemporary tools –Use general or self-determined guideline documents written for specific audiences –To refine systems, use feedback from individual or groups of users Raising the computer consciousness of the general public –Many novice users are fearful due to experience with poor product design, –Good designs help novices through these fears by being clear, competent, and nonthreatening