Evaluation Types GOMS and KLM PRICPE. Evaluation 10/30/2013. Where we are in PRICPE: Analytical based on your head Empirical based on data

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1 Evaluation Types GOMS and KLM PRICPE 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 due Design Gallery #1. Evaluate throughout, repeat iteratively!! 2 Evaluation Analytical based on your head Empirical based on data Formative informs design what is (still) needed? Summative did it work? 1

2 Analytical methods You follow established guidelines/procedures/models to decide (in your head) how good your design is. Examples: GOMS/KLM for skilled users, no errors. evaluating efficiency of regular use. Heuristic Evaluation Cognitive Walkthrough for first-time users. evaluating ease of learning. 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. 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. 2

3 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. 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,... 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). 3

4 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. KLM Operators User Operators: 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). 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.) 4

5 KLM/GOMS example 1 (cont.) Used to: Understand cost of each. (break down participants actual costs). Rx :recent lists. WS/WX :search. KLM/GOMS example 1 (cont.) Use the breakdowns to compare costs to new UI alternative (new feature FP ) actual calc d Heuristic Evaluation One of the Discount usability methods Apply heuristic guidelines (eg: Nielsen s) to a UI to find problems. Who does it: Multiple usability experts. Example heuristics: ambient displays: pp (2 nd ed). web design: Box 15.1 (3 rd ed). Default: use Nielsen s: c_list.html 5

6 Heuristic Evaluation: How How: Pick some usability guidelines, experts, task. Brief the experts. Experts indep ly evaluate UI s conformance with those guidelines for that task (1-2 hrs.) Pass 1: flow. Pass 2: focus on specific UI details. Outcome: UI problems. Experts meet to discuss problems, assign priorities, suggest solutions. Heuristic Evaluation: Activity Applying this version of the guidelines to your projects: Cognitive Walkthrough Walk through the UI, asking yourself questions along the way. Who does it: 1 or more usability experts. (3 is ideal) How: Identify characteristics of user and task. Make up multiple copies of the Questions (next slide...) 6

7 Cognitive Walkthrough: How (cont.) Walk through the task while answering these Questions: Will the user know what to do? (Gulf of exec) Will the user see how to do it? (Gulf of exec) Will the user understand from feedback whether their action was correct? (Gulf of eval) Cognitive Walkthrough: How (cont.) Record the answers but also: Assumptions about what would cause the problems and why. Notes about side issues. Notes about possible solutions. Example for Amazon.com p. 516 (3 rd edition). Cognitive Walkthrough: Activity OSU has a shared car program: Suppose an OSU student wants to consider whether to use it. Walk through the steps of this task: Will s/he know what to do? (Gulf of exec) Will s/he see how to do it? (Gulf of exec) Will s/he understand from feedback whether the action was correct? (Gulf of eval) Notes: why, side-issues, ideas,... 7

8 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 8