Usability -1h

1. Usability -1h

2. Learning Outcomes • Readability • Navigation • Accessibility to challenged people • Testing to ensure that the changes to the site have indeed been improvements..

3. Definitions of Usability • Productivity: How fast or efficient can the user be with the help of this system? • Learnability: How easy is it for a newcomer to learn the system? • Memorability: When a user returns to the system, must they relearn it or will they be able to remember skills they learnt first time round. • Error frequency: How easily can the average user make mistakes? • Satisfaction: Does the system make the user feel inadequate? Do they enjoy using it?

4. More Definitions • The capability of the software product to be learned, used, and attractive to the user, when used under specified conditions (ISO/IEC 9126-1) • The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use (ISO 9241-11). • The ease with which a user can learn to operate, prepare inputs for, and interpret outputs of a system or component (IEEE Std. 610.12)

5. Readability Categories: • Titles • Page Length • Page Layout • Text presentation • Reading • Graphics

6. Titles • Use the <TITLE> tag • Give a good self-explanatory main title • Many users will have arrived via search engines • introduce the page so as to reorient these visitors • Use subheadings informatively • 79% of web users scan pages • scanners focus on titles rather than text

7. Page Length • Bailout rate is proportion who leave page before it has completely downloaded • Average background figure for bailout rate is about 8% • This climbs to around 27% for a download time of 8 seconds (around 40 k-bytes) • Many users don't bother to scroll scrolling pages

8. Page Layout • Line up the various elements vertically. • Background colours can lead the eye from one important point to another. • The impatient surfer may not want to scroll. • It is important to be consistent • You don't need to sacrifice readability, just to improve visual style.

9. Text presentation • Don’t use more than two point sizes on the page. • Text any smaller than ten-point is difficult to read; I aim for twelve-point. • Try to use a readable typeface. • Avoid the over-use of ornate decorative fonts.

10. Reading • Use a restricted vocabulary. • Too much solid text could frighten a user away. • Write scannable text: • Subtitles self-explanatory • Make link-text say something pithy • Gems within the text could be emboldened • Paragraphs should express only one idea

11. Graphics • Some will not be using monitors at all. • Use ALT text. • Don’t use graphics as links • Make links look like links: "mine sweeping" • Don’t hide the meaning of an image link until it is rolled over by the cursor.

12. Consistent Navigation Aids • Second nature • Found in conventional places • To where expects to go • To where wants to go • Breadcrumbs

13. Text-based Navigation • Use well chosen words • Images are ambiguous • Some will have images switched off • Some browsers don’t show images • Use ALT text and/or a caption which is also a link

14. Navigation and Links • Group your links into sensible groupings • Put them where people expect them • Sometimes more than one clump of links, in different zones of the page • (But also contextual navigation)

15. Navigation Map Design • Where am I? • Where can I go next? • How can I recover from an error? • The three-click rule • Put important information high up the navigation hierarchy

16. Accessibility: colour • Some won’t be using monitors • Fair number are colour blind (some don’t know it yet) • Can’t rely on client’s hardware

17. Accessibility: Alternative Formats • Some can’t perceive: • Graphics • Video • Sound • …So offer a text alternative! • Use ALT tag • Give text descriptions of videos etc

18. Accessibility: User Control • Slow readers have difficulties with: • Blinking text • Marquee • Timed slide shows • Give them the option of control

19. Testing Categories: • Usability inspection • Group Walkthrough • User Testing • Diary Studies • Server Statistics

20. Usability inspection • Expert Critique = • Trained professional goes through the site. • List of heuristics • Makes a note of any problem • Five independent experts better • Alternatively, ordinary person with a comprehensive checklist

21. Group Walkthrough • Group of non-designers • Try to carry out specified tasks. • people already involved in the conceptual design (e.g. users, directors, union representatives and office workers). • Facilitator suggests guidelines or faults to look out for

22. User Testing • Watch individual user do tasks • Reassure that test is of site and not of them • Mistakes are probably due to imperfect site design • Tasks deliberately made slightly general

23. Diary Studies • Some users are asked to make notes over a long period. • Not possible to see what they are actually doing • Long-term technique

24. Server Statistics • Which are your most/least popular pages • How long do people spend reading? • Success ratio of viewers to purchases • Where do they bail out? • What routes do they take through the site? • Onto which page do they generally arrive?