USABILITY

TESTING

Software Quality

Flexibility

Adaptability

ReadabilityTestability

Portability

Reusability

Interoperability

Expandability

Accountability

Understandability

Legibility

Maintainability

Reliability

EfficiencyIntegrity

Correctness

Maturity

Analyzability

Operability

Changeability

Adaptability

Stability

Installability

Replaceability

Learnability

Traceability

Usability

Perform better in demos and reviews, users more receptiveAre easier for first-time users to learn and use, reducing support costs

Characteristics of Usable Products:

Increase corporate user acceptance of internally developed systemsIncrease customer satisfaction and loyalty, increasing product use.

What is Usability ?What is Usability ?

Usability is the “effectiveness, efficiency and satisfaction with which a specified set of users can achieve a specified set of tasks in a particular environment

Usability is the “effectiveness, efficiency and satisfaction with which a specified set of users can achieve a specified set of tasks in a particular environment

ISO Definition:

How easy is it to learn a system ?

How efficiently can the users use the system once they have learned to use it ?

Is the system pleasant to use ?

How frequent are errors made and how serious are they ?

Is it easy to remember what to do ?

Usability Problems ?Usability Problems ?Usability problems are aspects of the user interface that may cause the system to have reduced usability.

Characteristics of the product that make it difficult or unpleasant for users to accomplish tasks supported by the product

Problem Severity:

The frequency with which the problem occurs. Is it common or rare?

The impact of the problem if it occurs. Will it be easy or difficult for the users to overcome?

The persistence of the problems : Is it a one-time event that users can deal with once they know how or will they repeatedly be bothered by the problem?

The market impact. What will the impact be on the popularity of the product?

Usability EvaluationsUsability EvaluationsUser Testing

empirical method of allowing end-users to use the system under monitoring of usability engineers who record the users reactions and problems.

User Testing

empirical method of allowing end-users to use the system under monitoring of usability engineers who record the users reactions and problems.

Usability Inspections

evaluations performed normally by usability specialists (some methods incorporate users and developers) who make a more detailed evaluation of the interface.

Types include: 1. Heuristic Evaluations 2. Pluralistic Walkthroughs 3. Consistency Inspections 4. Standards Inspections 5. Cognitive Walkthroughs

Usability Inspections

evaluations performed normally by usability specialists (some methods incorporate users and developers) who make a more detailed evaluation of the interface.

Types include: 1. Heuristic Evaluations 2. Pluralistic Walkthroughs 3. Consistency Inspections 4. Standards Inspections 5. Cognitive Walkthroughs

User TestingUser Testing

Users performing real task with a real system

Users must be a true representation of the target users

Evaluators video record the users throughout the evaluation and can see what the users are experiencing

Good at finding major problems and task related problems

Users are likely to miss minor problems

Cognitive WalkthroughCognitive Walkthrough

Focus is the ease of learning aspect of usability

Provides limited benefits when compared to other methods

Based on the theory of learning by exploration

Can be used early in the design process

Pluralistic WalkthroughsPluralistic Walkthroughs

Group activity involving developers, users, and human factors specialists work work through scenarios while discussing the usability issues associated with the interface.

Can only evaluate one course of action using the hardcopy medium

Can be used early in design with storyboards or mockups

Standards InspectionsStandards Inspections

Evaluation of an interface to determine compliance with a given standard such as OSF/Motif

Evaluation of an interface to determine compliance with a given standard such as OSF/Motif

Not related to tasks nor scenariosNot related to tasks nor scenarios

Uncovers such things as misplacement of menu items, failure to provide tabbing between groups in dialogue boxes or as in the examples below the misuse of wrong controls

Uncovers such things as misplacement of menu items, failure to provide tabbing between groups in dialogue boxes or as in the examples below the misuse of wrong controls

Misuse of Control Functions:Project Manager insisted that drop-down controls be used to collect information whenever possible due to his fear that some 400,000 corporate users were incapable of typing. The result was the following:

Misuse of Control Functions:Project Manager insisted that drop-down controls be used to collect information whenever possible due to his fear that some 400,000 corporate users were incapable of typing. The result was the following:

Standards Inspections (cont)Standards Inspections (cont)

Misuse of Controls:

In this example the developer should have used a drop-down controls. This type of interface is very inefficient for the user and makes the application slower while using more memory. Makes you wonder how the user would select his country and city?

Misuse of Controls:

In this example the developer should have used a drop-down controls. This type of interface is very inefficient for the user and makes the application slower while using more memory. Makes you wonder how the user would select his country and city?

Consistency InspectionsConsistency Inspections

Evaluation of the consistency across various parts of the product or product family

Distributed and segregated work results in developers making decisions on everything from terminology to placement of icons, window etc

Goal is to have the maximum level of consistency throughout the product or product family so users will be able to quickly learn how to use the system and find using the system easy

OKOK HelpCancel

OKOK

Help

Cancel

OKOK

Help

Cancel

OKOK HelpCancel

How Many Differences Can You Spot ?How Many Differences Can You Spot ?

Answer: Location Boxed OK Underlined H

Answer: Location Boxed OK Underlined H

Heuristic EvaluationHeuristic Evaluation

Guidelines or (Heuristics) used to judge the interface’s usability

One of the “discount usability engineering” methods

Method can be used in early stages of design using storyboards, screen printouts or prototypes

Evaluators inspect the interface on their own

Common HeuristicsCommon Heuristics

Visibility of system status

User control and freedom

Consistency and standards

Help and documentationError prevention

Aesthetic and minimalist design

Flexibility and efficiency of use

Irrelevant information should be deletedIrrelevant information should be deleted

Too much information. Can anyone spot the other error?

Where’s the ‘HELP’ button they say to press?

Common HeuristicsCommon Heuristics

Match between system and the real world

Visibility of system status

User control and freedom

Consistency and standards

Help and documentationError prevention

Aesthetic and minimalist design

Flexibility and efficiency of use

Recognition rather than recall

Geekspeak and System-Orientated TermsGeekspeak and System-Orientated Terms

How would a user know what to select ? Problem using the RGB hexadecimal numbers to represent the colour selection to the user.

This is an Internet Explorer window that lets users set the formatting for headers and footers printed from the browser. I am sure you all know what the sample specifies.

Common HeuristicsCommon Heuristics

Help user recognize, diagnose and recover form errors

Match between system and the real world

Visibility of system status

User control and freedom

Consistency and standards

Help and documentationError prevention

Aesthetic and minimalist design

Flexibility and efficiency of use

Recognition rather than recall

Error Messages Should be MeaningfulError Messages Should be Meaningful

Error Messages Should be MeaningfulError Messages Should be Meaningful

Miscellaneous PointsMiscellaneous PointsGroup vs Individual Evaluators

Individual evaluators have been shown to uncover approximately 35% of the usability errors

Optimum number varies between 3 and 5

What Method Should I Use ?

No single method will find all usability problems

Use a combination of complementary methods

Miscellaneous PointsMiscellaneous Points

When Should I Evaluate

The earlier the better

Iteratively

Developer “Buy-In”

Seeing is believing - Video tape user tests

Incorporate the developer into the evaluation process

What’s in it for Me ?What’s in it for Me ?

Usability problems cost money to fix. The earlier they are discovered the less they cost to fix

A more usable product is a better product and a better product will be better accepted and make more money

If you can’t afford the time and resources to do it rightcan you afford the time and resources do do it over?

ConclusionConclusionUsability is an aspect of Software Quality.

Usability is defined as the ease at which user learn and use the system coupled with the overall experience they have with the product.

Usability problems are problems that adversely effect the usability of the product.

Usability can be assessed by User Testing and Usability Inspection.

The best approach is to use both User testing and Usability Inspections throughout the development cycle to improve the quality of the product