Interface evaluation

An application of evaluative methods

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Today’s topics

• Research methods• Web application • Navigation• Link structure (see slides in week)• Image (see slides in week)• Interactivity• User Information Behavior and Design Implications• Artifact models• Examples with questionnaires

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Research methods

• Survey• Interviews• Focus groups• Observations/Contextual Inquiry• Usage Statistics, Log Analysis• Usability Testing• Card Sorting

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Comparison (I)Research Methods Pros and Cons Best Used for

Survey Pros: Reach many people without geographical barriers.Cons: Low response rate. Ambiguity in question and/or answer. Subjective and retrospective.

Collect preferences and opinions from one or many large group(s).

Interviews Pros: No ambiguity, can ask follow-up questions to probe unexpected topics or clarify issues. Easy to conduct.Cons: Subjective and retrospective.

Understand business stakeholders and their objectives. Gain quick understanding about issue, problems and questions based on verbal report.

Source: Ding, W. & Lin, X. (2010). Information architecture: The design and integration of information spaces. Morgan & Claypool Publishers.

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Comparison (II)Research Methods Pros and Cons Best Used for

Focus Groups Pros: Like a group interview.Can reach multiple people at the same time. Participants may be inspired by each other and provide more valuable ideas.Cons: Participants’ opinionsmay be influenced by others. Out of context of the task.

Collect opinions, ideas and visioning data. Good for high-level starting points and trend data.

Observations/Contextual Inquiry

Pros: Data gathering takes place in the context of user’s work. Data is more concrete. Data is more objective, natural. Cons: Opportunistic, time consuming, large amount of data, analysis takes time.

Understand user tasks based on behavior. Understanduser’s working environment.

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Comparison (III)Research Methods Pros and Cons Best Used for

Usage Statistics, Log Analysis

Pros: Data is objective and rich. May discover in-depth information about user failure.Cons: Sheer volume of data. Need coding or special software to do analysis.

Identify usage patterns and find problems that need research.

Usability Testing Pros: Rich data both verbaland behavioral. Cons: Lab setting and artificialtasks may decrease the value of the data.

Effective in identifyingdesign defects.

Card Sorting Pros: Powerful tool can be used both qualitatively andquantitatively.Cons: Results need to be presented in a meaningful way.

Best used for studyingusers’ mental models

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Three Generations of the Web (I)

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Three Generations of the Web (II)

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Web Applications

Source: Ding, W. & Lin, X. (2010). Information architecture: The design and integration of information spaces. Morgan & Claypool Publishers.

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Web 2.0 applications

• Wiki, blog, and SNS

Example: Campaign websites

Sum

Barack Obama Y Y Y Y Y 5Michele Bachmann Y Y Y Y Y Y Y 7Ron Paul Y Y Y Y Y Y 6Rick Perry Y Y Y Y Y 5Mitt Romney Y Y Y Y Y Y Y 7Sum 5 5 5 2 5 3 5

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Navigation (I)

• Purpose of navigation– Where am I? (orientation).– What can I do? (content, interaction, search).– Where can I go from here?• Drill up via global navigation.• Parallel move via local navigation.• Drill down via associative navigation.

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Navigation (II)

• Navigation types– Global navigation and sectional navigation– Local navigation– Supplemental navigation– Process navigation

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Compare the two navigation systems

• http://www.libraries.iub.edu/index.php• http://www.lis.illinois.edu/

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Interaction Design Principles

• Design for Fitts• Design for Color Blindness• Design for Affordance• Design for Efficiency• Design for Forgiveness• Design for User Perceptions

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Fitt’s law: Design for Fitts

• Fitts’ Law maintains that the time required to move rapidly from a starting point to a final target area is a function of the distance to the target and the size of the target.

• Bigger is better: Important functions should be presented with large objects (reasonably big).

• Closer is faster: The contextual action buttons or links should be presented within the reasonable proximity of user activities.

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An example

• Which one is better?

• What about this?

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Design for color blindness

• Besides color, they also use shapes to convey the information.

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Design for affordance

• An affordance is whatever can be done to an object– a chair affords sitting– a button affords pushing– a handle afford turning or pulling

• To ensure perceived affordance, the design should meet user expectations. Following conventions usually gives good affordance– Make sure people can easily tell which is clickable and

which is not

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Design for efficiency

• Efficiency allows the user to accomplish the task more quickly

• Ways to ensure efficiency– decreasing data entry (Amazon)– limiting decision making on the user’s side

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Design for forgiveness

• Forgiveness allows the user to feel less anxiety about making mistakes, and allows for imperfections in human activity.

• There are different ways to offer forgiveness– Easy reversal of actions ((are you sure?) dialogs)– Error prevention– Error handling

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Design for user perceptions

• User perceptions are not always right• However, it is very important for designers to

be aware of it during the design process• It is important to provide multiple ways to

accommodate different users so that they can choose the preferred method to perform their tasks

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An example• A classic example occurred in the 1930s in New York City, where

“users” in a large new high-rise office building consistently complained about the wait times at the elevators. Engineers consulted concluded that there was no way to either speed up the elevators or to increase the number or capacity of the elevators. A designer was then called in, and he was able to solve the problem.

• What the designer understood was that the real problem was not that wait time was too long, but that the wait time was perceived as too long. The designer solved the perception problem by placing floor-to-ceiling mirrors all around the elevator lobbies. People now engaged in looking at themselves and in surreptitiously looking at others, through the bounce off multiple mirrors. Their minds were fully occupied and time flew by.

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How people use websites (I)

• Users first read in a horizontal movement, usually across the upper part of the content area. This initial element forms the F’s top bar. Next, users move down the page a bit and then read across in a second horizontal movement that typically covers a shorter area than the previous movement. This additional element forms the F’s lower bar. Finally, users scan the content’s left side in a vertical movement.http://www.useit.com/alertbox/reading_pattern.html.

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How people use websites (II)

• Users tend to sacrifice information quality for easy access (e.g. Wikipedia vs. Encyclopedia)

• Relying more on web search engines than individual websites

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Work models

• Work models– Work models = a graphical language to capture

knowledge about work– Models make concepts concrete, in order for the

team to share and discuss ideas– Models can be used to communicate with clients

• Types of work models– Flow model, sequence model, culture model,

artifact model, and physical model

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Artifact model

• Artifacts are tangible things people create or use to help them get their work done

• Presentations– Information presented by the object– Parts of the object– Structure of the parts– Annotations– Presentation– Additional conceptual distinctions– Usage– Breakdowns

• A few examples

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Questionnaires on interface evaluation

• http://oldwww.acm.org/perlman/question.htmlAcronym Instrument Reference Institution ExampleQUIS Questionnaire for User

Interface SatisfactionChin et al, 1988 Maryland 27 questions

PUEU Perceived Usefulness and Ease of Use

Davis, 1989 IBM 12 questions

NAU Nielsen's Attributes of Usability

Nielsen, 1993 Bellcore 5 attributes

NHE Nielsen's Heuristic Evaluation Nielsen, 1993 Bellcore 10 heuristics

CSUQ Computer System Usability Questionnaire

Lewis, 1995 IBM 19 questions

ASQ After Scenario Questionnaire Lewis, 1995 IBM 3 questions

PHUE Practical Heuristics for Usability Evaluation

Perlman, 1997 OSU 13 heuristics

PUTQ Purdue Usability Testing Questionnaire

Lin et al, 1997 Purdue 100 questions

USE USE Questionnaire Lund, 2001 Sapient 30 questions