1. Analytical Evaluation with GOMS and KLM
CS352

2. Announcements Notice upcoming due dates (web page).
Where we are in PRICPE:
Predispositions: Did this in Project Proposal.
RI: Research was studying users. Hopefully led to Insights.
CP: Concept and initial (very low-fi) Prototypes in Design Gallery #1.
Evaluate throughout, repeat iteratively!!

3. GOMS (and KLM) GOMS: a family of models. Predict user performance.
Useful for predicting actual time a skilled user will take in UI.
Useful for comparing different UIs.

4. GOMS Constructs Goal, Operators, Methods, Selection rules
Goal: “what”.
Method: “how” steps (learned).
Operators: Cognitive processes + physical actions to DO it.
Selection rules: rules saying which method to select.

5. GOMS example: Delete a word
Goal: delete a word in a sentence.
Method #1: use the menu
Recall that the word has to be highlighted.
Recall that the command is “cut”.
Recall that “cut” is in the Edit Menu.
Accomplish goal of selecting and executing “cut”.
Return: goal accomplished.

6. GOMS example (cont.) Method #2: use the delete key
Recall where to position cursor in relation to word to be deleted.
Recall which key is delete key.
Press “delete” key to delete each letter.
Return: goal accomplished.
Operators used in these methods
Click mouse, Drag cursor over text, Select menu, Move cursor, Press KB key, Think, ...

7. GOMS example (cont.) Selection rules:
Use mouse/menu method (#1) if there’s a lot of text to delete.
Else use “delete” key (method #2).

8. KLM (a low-level variant of GOMS)
Keystroke Level Model.
Simple, but accurate. Widely used.
Scope:
skilled users
doing a task error-free.
using a specific method in a UI.
CogTool has this built-in.

9. KLM Operators User Operators: System Operator:
K (keystroke), P (point), H (homing), D (drawing), M (mental: think).
Times for each are provided to you
based on extensive research/empirical data.
System Operator:
R (respond).

10. KLM/GOMS example 1: Open a file
27 ways to open a file in Windows!
Methods as states + transitions.
(High op granularity combines low-level ops.)

11. KLM/GOMS example 1 (cont.)
Used to:
Understand cost of each.
(break down participants actual costs).
“Rx”:recent lists.
“WS/WX”:search.
And to...

12. KLM/GOMS example 1 (cont.)
Use the breakdowns to compare costs to new UI alternative (new feature “FP”)
actual
calc’d

13. Comparison GOMS/KLM vs. HE vs. CogWalk how long it takes you to do
how much detail it gives you
about what kind of user
how much of the UI you focus on at once