A Usability Framework for Mobile Websites (2012)

Shackle (1991)

About Usability

Friday, June 15, 2012 Bi5 Agency Sondra L. Duckert Bachelor Thesis Exam E-Concept Development TEAM 3, Third Semester

Nielsen (2000)

Preece (1994)

Defining usability

Defines usability as:

Defines usability as:

Defines usability as:

The definition of usability is influenced by the experience of those who proposed the definitions and the domain in which they practiced usability. Common factors linking the definitions are the user, the task, the technology and the context of use.

"A system's capability in human functional terms to be used easily and effectively by the specified range of users, given specified training and support, to fulfill a specified range of task, within the specified range of environmental scenarios."

"A measure of the ease with which a system can be learned or used, its safety, effectiveness and efficiency, and the attitude of its users towards it."

"The engineering ideal of solving a problem for the consumer," and it aims to place "your customers' needs at the center of your Web strategy."(2000)

A Common Thread

Perceptions of Usability As a Quality Factor Model

Usability Attributes

Perceptions of Usability based on

Effectiveness

McCall Shackle

Efficiency

Satisfaction

Learnability

Operability

Communicativeness

Training

Effectiveness Flexibility

Subjectively Pleasing

Learnability

FURPS

Consistency

Human factors

Aesthetics

Online and context sensitive help Wizards and agents User documentation

Nielsen

Errors

Efficiency

Satisfaction

Learnability Memorability

Preece et al.

Effectiveness

Efficiency

Enjoyableness

Preece et al.

Flexibility

Efficiency Throughput

Attitude

ISO 9241-11

Effectiveness

Efficiency

Satisfaction

ISO 9126-1

Operability Usability Compliance

Donyaee et al.

Effectiveness Accessibility Universality Usefulness

Abran et al.

Schneiderman et al.

Safety

Safety Learnability

Attractiveness

Understandability Learnability

Efficiency Productivity

Satisfaction Trustfulness

Learnability

Safety

Effectiveness

Efficiency

Satisfaction

Learnability

Security

Rate of errors by users

Speed of performance

Subjective Satisfaction

Time to learn Retention over time

Social acceptability

easy to learn

Usefulness Usability

cost compatibility

Practical acceptability

reliability

efficient to use

etc.

A model of attributes of system acceptability (Nielsen, 1993)

Image Source: Brian Fling

Usability together with utility are considered to influence the usefulness of the product. Usefulness is one of the attributes affecting acceptability.

(Nielsen 1993)

speed

effectiveness

Usability

few errors subjectively pleasing

flexibility

attitude

easy to remember

errors

learnability time to learn

Acceptance

System acceptability

Utility

Utility

retention

Likeability Costs Product acceptance (Shackle 1991)

ISO 9241

About Usability

(1998)

Friday, June 15, 2012 Bi5 Agency Sondra L. Duckert Bachelor Thesis Exam E-Concept Development TEAM 3, Third Semester

ISO 25010

ISO 9126

(2011)

(2001)

Context of Use

Quality of Use

SQuaRE Model :

"Usability is the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and with satisfaction in a specified context of use."

"Usability is the capability of the software product to be understood, learned, used and attractive to the user, when used under specified conditions."

Product Quality and Quality in Use

'Usability is a property of the overall system: it is the quality of use in a context.'

"Usability can either be specified or measured as product quality characteristic in terms of its sub-characteristics, or specified or measured directly by measures that are a subset of quality in use."

Software Quality Factors for Evaluation

Usability and Quality intended objectives

ISO/IEC 9126-1

goals

users usability: extent to which goals are achieved with effectiveness, efficiency and satisfaction

task

ISO 9126-2 External Metrics

Sub-characteristics

ISO 9126-3 Internal Metrics

Characteristics Suitability

equipment

Maturity effectiveness

Accuracy

outcome of interaction

Fault Tolerance efficiency

Context of use

Security Recoverability

satisfaction

product

Functionality

Interoperability Compliance

Quality of use measures

Compliance

Usability framework

Reliability Analyzability

Quality ISO/IEC 9126

ISO 9241

Time behavior

Change-ability

Resource utilization

Stability

Compliance

Testability

Efficiency

Maintainability

Metrics

environment

Compliance Adaptability

Portability

ISO 25010

Install-ability

Understandability

Co-existance

Learn-ability

Replace-ability

Operability

Usability

Product Quality

Attractiveness

Compliance

Interoperability Co-existence

Compatibility Functional Su i ta b i l ity

Installability Replaceability Adaptability

Availability Maturity Recoverability

ISO 25010

Efficiency

Eff ect iv eness

Effi ciency

Fault tolerance

M aint a i n a b i l i t y

Testability

Time behavior Resource utilization Capacity

Effectiveness

Reliability

Reusability Modifiability

Quality in use

Po r ta bi l i t y

Modularity

Analyzability

Compliance

Functional completeness Functional correctness Functional appropriateness

Usability Per f o rm a n ce E f fi c i e n c y

Usefulness Trust Pleasure Comfort

ISO 25010 Sat isf act ion

Economic Risk Mitigation Health and Safety Risk Mitigation

Learnability Confidentiality Integrity Non-repudiation Accountability Authenticity

Appropriateness recognizability Operability

Sec urit y

User error protection User interface aesthetics Accessibility

Fre e d o m from risk

Context Coverage Context Completeness Flexibility

Environmental Risk Mitigation

About Usability

Guidelines

Friday, June 15, 2012 Bi5 Agency Sondra L. Duckert Bachelor Thesis Exam E-Concept Development TEAM 3, Third Semester

Goals

Metrics

'A Usability Framework for mobile Web sites: How usability attributes and metrics can help in optimizing mobile Web sites. A literature review.'

Attributes and Metrics

Usability Framework Foundation of a Usability Framework: A metric for evaluation, based on usability goals and guidelines.

No.

Guidelines

Explanation The accuracy and completeness with which users achieve specified goals.

1

Accuracy

2

Response time

3

The system should be easy to learn and Ease of learning understand.

4

Task accomplish- The time it takes to complete a task successfully. ment Expectation

6

Attractiveness

The capability of the software product to be attractive to the user.

7

Error tolerant

Errors made by the user while completing a task.

8

Pleasure

The extent to which the functions that a system provides matches the needs of the user.

9

Trustfulness

10

Engaging

How satisfying is it for a user to interact with a system.

11

Features

Relevant system features are available.

12

Performance

The system performance relative to the amount of resources used under stated conditions.

13

Reading

The time it takes to read a text screen.

15

❖ ❖

The objective was to develop a set of metrics derived from a question format.

This study used the Goal Question Metrics (GQM) method (Basil et al. 1994) for software quality improvement and measurements.

The first step in the GQM approach is to identify the goal, then propose a set questions in how to achieve the goal and lastly use metrics to determine its value.

The selected guidelines are accompanied by questions that will appraise each goal. The goal is then refined into several questions to ensure that they are measurable.

How difficult it would be complete a task.

Quality characteristics

Goal

Accuracy Effectiveness

The trust that a user has, in that the software will function properly.

Provide support/ The system should provide assistance to those that need additional help.

Help User effort

❖

A system must respond promptly.

5

14

❖

Task accomplishment Features Efficiency Performance

Safety Satisfaction Attractiveness

Guidelines - No errors (few errors) - Successful completion of tasks - Accurate - Ease to input data - Ease of system usage - Support/help - Time response - Completed tasks - While using the system - Confidence in the system - User interface

The extent to which the software produces suitable results equal to the user investments.

Questions How many links completed without site abandonment?

Does the site provide balance?

Metrics Time taken to learn each task

How accurate is the site information?

Measures

Guidelines Goals

How easy is it to input data?

Is the site easy to learn?

Are required fields highlighted?

Provide support/help Is the site flexible Number of errors Successful site browsing

Accuracy

The number of features

Effectiveness

The number of input actions Task Accomplishment

Features

Efficiency

Does the site provide support or help?

Amount of resources used

Does the site provide search filter options?

Site optimization (screen size)

Does the site provide local search functions?

Does the website load quickly?

How much interactivity is available on the site?

Performance

Time it takes to connect to a network Site response time Provide data protection

Rating scale for: Safety

Satisfaction

Are links safe for clicking?

How do users perceive the website?

Attractiveness

Are privacy measures in place?

Will users remember the aesthetics?

- Support - Input/output - Features - Interface - Site flexibility

Physical context

About Usability

Friday, June 15, 2012 Bi5 Agency Sondra L. Duckert Bachelor Thesis Exam E-Concept Development TEAM 3, Third Semester

Media context

Present location

Device of access

"Physical context will dictate how I access information and therefore how I derive value from it."

The media context isn't just about the immediacy of information we receive.

It's about how we engage people in real time.

Modal context Modal Context Our present state of mind.

"Where should I eat" Should I buy it now or later?

Is this safe or not?

Excerpts from, Designing Mobile Experiences with Brian Fling (2009)

Context Matrix

Usability and Context 'Usability cannot exist without first defining the context of the system being tested.'

'How will users derive value from something they are currently doing?'

What about 'mental models'?

At-a-Glance Location-based Content-based Task-based Full Screen

Context social and organizational environment

task goals

physical environment technical environment

interaction

user

tasks

product

'Usability is a function of the context in which a product is used e.g. the users, task, technology and environment.'

(Bevan 1994)

Satisfaction

Performance: Effectiveness & Efficiency

*Quality of Use measures *Quality of use measures determined by the Context of Use, ISO 9241-11 (Bevan, 1995)

Image Source: Brian Fling