Usability is not an add-on

1
Usability is not an add-on

• Steven PembertonCWI, Amsterdam

2
A thought experiment

• What are the features of websites that you go
  back to regularly that differentiates them from
  other websites with the same purpose?

3
Differentiating features

• Forrester did some research in this
• Good content (75)
• Usability (66)
• Speed (58)
• Frequency of updating (54)
• (The rest is noise 14 and lower)

4
This is surprising

• User testing is the first item to go when looking
  for reduced costs
• Many web-building companies have no usability
  experts on their staff
• Many web-building companies build sites that are
  measurably unusable

5
What is usability?

• It can be summarised by three factors
• Efficiencyhow quickly you achieve what you want
• Effectiveness how correctly you achieve it
• Satisfaction how much you enjoy doing it

6
Compromises

• Sometimes these factors have to be balanced out
• An experiment with 3 chess-playing interfaces
  (command-line, mouse, and real manipulation of
  chess pieces) showed that the mouse was the
  fastest
• But with real manipulation, the user won more
  often (was more effective)

7
Surprises

• The psychology of human beings can cause some
  surprising results
• In a test with three methods of writing (pen on
  paper, a text editor, a word processor) users
  wrote less with a pen but of a higher quality,
  more with a text editor but of a lower quality,
  and more with a word processor but with a higher
  quality.

8
Transparency

• A fourth aim of user interfaces is transparency
  you dont notice a good user interface, you spend
  all your time solving the problem.