1. Classification of Users

2. 4 What assumptions can be made about target users’ groups in terms of: –expected frequency of use of system –knowledge of task domain –knowledge of computers –general abilities literacy, vision –attitude towards computers in general/particular system –existing skills e.g., keyboard skills 4 Users can be classified in many ways to help define general user requirements –e.g., occupational expertise, level of computer expertise

3. Three dimensional framework for user classification (Low) knowledge of computers frequency of use knowledge of task (High)

4. Occupational categorisation of user groups 4 A broad occupational classification –computer professionals –professionals without computer experience –skilled clerks –naive users –special groups

5. Computer Professionals 4 Classification computer knowledge high/very high task knowledge high frequency of use high –understand software and hardware –intelligent, well-educated, highly motivated –may want to customise software –have little patience; need rapid response –sensitive to shortcomings in software –NOT typical of majority of users

6. Computer Professionals - design implications 4 provide for high degree of sophistication in interface in terms of –range of functions provided –flexibility to combine functions to produce new commands –possibilities of customising interface 4 lower than normal requirement for user support 4 can utilise programming languages, command scripts etc.

7. Professionals without computing experience 4 Classification computer knowledge low/moderate task knowledge high frequency of use varies –know little about computers –often uninterested in computers –probably have not read documentation –lack patience –have high expectations of performance –intolerant of software error –motivated by need to accomplish job/task –may be discretionary users of system –high degree of usability is critical

8. Professionals without computing experience - design implications 4 important to support user experimentation 4 consistency and close match to task model are important 4 frequency of use determines how much can be learned e.g., short cuts, accelerators 4 user support important in interface

9. Skilled clerks 4 Classification computer knowledge low task knowledge high frequency of use high –may use machine several hours per day –develop very strong user skills –do not have high degree of computer sophistication –require rapid responses –quickly grow impatient with features designed for less experienced users if such features slow them (i.e., skilled clerks) down –usage not usually discretionary

10. Skilled Clerks - design implications 4 Can anticipate significant learning of routine operations, therefore use abbreviations, hot keys etc. for data input 4 Can expect strong user skills to develop –e.g. keying skills 4 error messages must be clear, providing specific guidance for recovery, avoiding computer jargon 4 Cannot expect users to develop deeper computer system knowledge without specific training

11. Naive users 4 Classification computer knowledge very low task knowledge varies (low-moderate) frequency of use - assume to be low –know (nearly) nothing about computers –cannot assume significant learning process (each session of interraction should be treated as if the first) –may suffer from “technophobia” –ease of learning is important usability criterion - high degree of usability is essential –use of system usually discretionary

12. Naive users - design implications 4 every type of user error must be trapped 4 this type of user will not be able to infer cause of an error condition 4 explicit on-screen prompts required for each step of the dialogue 4 high degree of user support, low degree of sophistication at the interface

13. Special user groups 4 e.g., children –interface should be fun to sustain interest –should allow exploration and discovery (robust with minimal error conditions) –should provide rapid feedback and competitive element where appropriate –great care needs to be taken re. assumptions about reading skills, and understanding of task and/or computer concepts 4 e.g, handicapped/special needs –I/O devices often very important and may need customising –this group often ignored by hardware/software producers –specific needs of special groups dictate specific design considerations