1. COMP5047 Pervasive Computing: 2012 GOMS and keystroke predictive methods Judy Kay CHAI: Computer human adapted interaction research group School of Information Technologies

2. COMP5047 Pervasive Computing: 2012 2 Overview Predictive methods GOMS and keystroke analyses Benefits Disadvantages Adapting GOMS to Pervasive Computing (>1 million Google matches)‏

3. COMP5047 Pervasive Computing: 2012 3 Postconditions for this week (incl private study)‏ Describe the uses of GOMS Describe the processes for conducting GOMS analyses Describe advantages and limitations Ability to perform a GOMS study on conventional interfaces and explore the approach for pervasive systems Justify the use of GOMS in the overall testing of a pervasive computing application

4. COMP5047 Pervasive Computing: 2012 4 GOMS Goal Operations - keystrokes, clicks Methods - sets of operations Selection rules - decide between methods For expert users

5. COMP5047 Pervasive Computing: 2012 5 GOMS example (Newman and Lamming)‏ Make "the cat" bold in "the cat sat on the mat" Goal - to make "the cat" bold Operations - keystrokes, clicks Methods - ctrl-b or mouse/menu Selection rules - which method?

6. COMP5047 Pervasive Computing: 2012 6 K - keypress P - point with mouse C - click with mouse H - home hands on new device M - mentally prepare R(t) - system response time

7. COMP5047 Pervasive Computing: 2012 7 K – keypress.08 - 1.20 P - point with mouse.8 - 1.5 (Fitt's Law)‏ C - click with mouse.2 H - home hands on new device.4 M - mentally prepare 1.35 R(t) - system response time ? How would you determine values for a pervasive system?

8. COMP5047 Pervasive Computing: 2012 8 NOTES: M before K/C or P except PMK... PK if K “anticipated” –e.g. move mouse to target and click MKMKMK... MKKK for cognitive unit –e.g. type “cat”

9. COMP5047 Pervasive Computing: 2012 9 Method 1 – highlighting “the cat” Assumptions: hands were on keyboard and R = 0. H - 0.40 - Reach for mouse M – 1.35 – mentally prepare P - 1.10 - Point to the left of "the" C - 0.20 – Click mouse M – 1.35 – mentally prepare P - 1.10 - Point to right of "cat" C - 0.20 - Release mouse Total = 5.7

10. COMP5047 Pervasive Computing: 2012 10 Method 1 cont – bolden keyboard shortcut M – 1.35 – mentally prepare K - 0.60 - Press and hold "Control" K - 0.60 - Press "B" K - 0.60 - Release "Control" Total = 3.15

11. COMP5047 Pervasive Computing: 2012 11 Method 2 - use menu Assumptions: hands were on keyboard and R = 0  M – 1.35 – mentally prepare P - 1.10 - Point to "Format" menu C - 0.60 - Click and hold M – 1.35 – mentally prepare P - 1.20 - Point to "Bold" menu item C - 0.60 - Release mouse Total = 6.2

12. COMP5047 Pervasive Computing: 2012 12 Conclusion for this case Assumtions: Hand position, R, K, P Common part is 5.7 (sweeping out “the cat”)‏ Rest of –Keyboard shortcut takes 3.15 seconds –Mouse menu method takes 6.2 seconds

13. COMP5047 Pervasive Computing: 2012 13 Summary of approach Focus on speed Known sequence of operations Can predict performance for experienced users Walkthrough steps, calculate time for each step, sum Can sometimes predict choices of method

14. COMP5047 Pervasive Computing: 2012 14 Summary of uses Relatively inexpensive Can be used to compare “methods” Challenging to apply for conventional interfaces.... pervasive? Expert users only Would you expect software that assist in this?