Lecture 11

Question 1

Heuristic evaluation

Answer 1

Heuristic evaluation is a review guided by a set of heuristics.

A heuristic technique is an approach to problem-solving that employs a practical method not guaranteed to be optimal but sufficient for the immediate goals.
Design principles form a basis for developing heuristics.

Question 2

Nielsen’s Original Heuristics

Answer 2

Visibility of system status.
Match between system and real world.
User control and freedom.
Consistency and standards.
Error prevention. 
Recognition rather than recall.
Flexibility and efficiency of use.
Aesthetic and minimalist design.
Help users recognize, diagnose, recover from errors.
Help and documentation.

Question 3

Discount Evaluation

Answer 3

Heuristic evaluation is referred to as discount evaluation when 5 evaluators are used.

Question 4

Cognitive walkthroughs

Answer 4

Focus on ease of learning.

Designer presents an aspect of the design & usage scenarios.

Expert is told the assumptions about user population, context of use, task details.

One or more experts walk through the design prototype with the scenario.

Question 5

Pluralistic walkthrough

Answer 5

Variation on the cognitive walkthrough theme.

Performed by a carefully managed team.

The panel of experts begins by working separately.

Then there is managed discussion that leads to agreed decisions.

The approach lends itself well to participatory design

Question 6

Predictive Models

Answer 6

Provide a way of evaluating products or designs without directly involving users.

Less expensive than user testing.

Usefulness limited to systems with predictable tasks - e.g., telephone answering systems, mobiles, cell phones, etc.

Based on expert error-free behavior.

No experts mimicking users, no analytics of use.

Instead analyses tasks and keystroke patterns.

Question 7

GOMS

Answer 7

Goals – what the user wants to achieve e.g. find a website.

Operators - the cognitive processes & physical actions needed to attain goals, e.g. decide which search engine to use.

Methods - the procedures to accomplish the goals, eg. drag mouse over field, type in keywords, press the go button.

Selection rules - decide which method to select when there is more than one.

Question 8

Fitts Law

Answer 8

Fitts’ Law predicts that the time to point at an object using a device is a function of the distance from the target object & the object’s size.

The further away & the smaller the object, the longer the time to locate it & point to it.
Fitts’ Law is useful for evaluating systems for which the time to locate an object is important, e.g., a cell phone, a handheld devices.