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User Studies: Surveys and Continuing AssessmentLecture 5

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Case Study: One-Or-More Buttons

Task: Good control that gives the user a "one or more, but not none" selectionCross between radio buttons and check

boxesSelect as many as want, but always keep at

least one selected

from Bruce "TOG" Tonazzini's TOG on Interface, 1991

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Approaching the Problem

Guidelines for expanding an interface If it ain't broke real bad, don't fix it Build on existing visual/behavioral language Invent new objects, with new appearances, for new

behavior When possible, evolve objects, rather than starting

from scratch Make changes clearly visible Interpret users' responses consistently Multiplex meanings

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Constraints

People have to figure out how to use the control on their own, first time out

Appearance reflect marriage between radio buttons and check boxes

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Ten Steps for User Testing on the Cheap

1. Introduce yourself

2. Describe the purpose of the observation (in general terms)

Stress you want to find problems in the product

3. Tell the participant that it's OK to quit at any time

4. Talk about the equipment in the room

5. Explain how to "think aloud."

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Ten Steps for User Testing on the Cheap

6. Explain that you will not provide help

7. Describe the tasks and introduce the product

8. Ask if there are any questions before you start; then begin the observation

9. Conclude the observation

10. Use the results

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The Paper Test

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Next Iteration

Response to first iteration

More designs Testing

Thought it looked like an icky bug X meant it was inactive (cancelled) Thought rule was that you had to use a particular

English

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3rd Iteration

Next design: Test 5 subjects

None develop superstitious ruleThe object work!

But…Prototypes started with at least two buttons on If they go locked up, hound them until they try

clicking the immutable button

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Peer Design Review

What was the funny looking line? New design:

The superstitious rule came back

Solving the superstitious rule Mimic mercury: Pressing the only button turned on will

cause it to turn off and the button below to turn on

Test: 11 year old son immediately knows the rule

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Final Design

Validation Testing 5 people

2 nine year olds woman who uses a Mac 2 hours per week woman who uses a Mac 2 hours per day self-identified power-user

All learned rule within 15 seconds

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Survey Instruments

Written user surveys are a familiar, inexpensive and generally acceptable companion for usability tests and expert reviews.

Keys to successful surveys Clear goals in advance Development of focused items that help attain the goals.

Survey goals can be tied to the components of the Objects and Action Interface model of interface design.

Users could be asked for their subjective impressions about specific aspects of the interface such as the representation of:

task domain objects and actions syntax of inputs and design of displays.

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Surveys (cont.) Online surveys avoid the cost of printing and the extra effort

needed for distribution and collection of paper forms.

Many people prefer to answer a brief survey displayed on a screen, instead of filling in and returning a printed form,

although there is a potential bias in the sample.

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Acceptance Test

For large implementation projects, the customer or manager usually sets objective and measurable goals for hardware and software performance.

If the completed product fails to meet these acceptance criteria, the system must be reworked until success is demonstrated.

Rather than the vague and misleading criterion of "user friendly," measurable criteria for the user interface can be established for the following:

Time to learn specific functions Speed of task performance Rate of errors by users Human retention of commands over time Subjective user satisfaction

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Acceptance Test (cont.) In a large system, there may be eight or 10 such tests to carry out

on different components of the interface and with different user communities.

Once acceptance testing has been successful, there may be a period of field testing before national or international distribution.

Yes or no decision - is it good enough to release?

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Evaluation During Active Use

Interviews and focus group discussions Continuous user-performance data logging Online or telephone consultants Online suggestion box or e-mail trouble

reporting Discussion group and newsgroup

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Controlled Psychologically-oriented Experiments

Scientific and engineering progress is often stimulated by improved techniques for precise measurement.

Rapid progress in the designs of interfaces will be stimulated as researchers and practitioners evolve suitable human-performance measures and techniques.

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Controlled Psychologically-oriented Experiments (cont.)

The outline of the scientific method as applied to human-computer interaction might comprise these tasks: Deal with a practical problem and consider the theoretical framework State a lucid and testable hypothesis Identify a small number of independent variables that are to be

manipulated Carefully choose the dependent variables that will be measured Judiciously select subjects and carefully or randomly assign

subjects to groups Control for biasing factors (non-representative sample of subjects or

selection of tasks, inconsistent testing procedures) Apply statistical methods to data analysis Resolve the practical problem, refine the theory, and give advice to

future researchers

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Controlled Psychologically-oriented Experiments (cont.)

Controlled experiments can help fine tuning the human-computer interface of actively used systems.

Performance could be compared with the control group.

Dependent measures could include performance times, user-subjective satisfaction, error rates, and user retention over time.