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Università degli Studi di Torino

Dottorato di Ricerca in Informatica (XVII ciclo) Tesi di Dottorato

Web Usability: Roots And Approaches Andres Baravalle

Relatore: Prof. Luca Console Coordinatore: Prof. Pietro Torasso

Anni accademici 2000-2003

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Table of Contents

Table of Contents

Table of Contents... II

Introduction...1

Usability Culture ...4

1.1 What Usability Means ...5

1.2 Usability roots ...8

1.2.1 Ergonomics ...8

1.2.2 Human Factors ...10

1.2.3 Human Computer Interaction...11

1.3 Return of Investment ...13

1.4 Design...14

1.5 Legislation and Guidelines...15

1.6 Usability and Information Technology...16

Web Usability...17

2.1 Web Accessibility ...18

2.1.1 Examples of Web Accessibility...22

2.1.2 Web Usability and Web Accessibility...22

2.1.3 Design for All ...23

2.1.4 Guidelines for Accessibility...25

2.1.5 Accessible Web Sites...26

2.2 Web Usability Studies...27

2.3 Usability Design Phases ...28

2.3.1 Gearing Up Phase ...31

2.3.2 Initial Design Phase...31

2.3.3 Iterative Development Phase...31

2.3.4 System Monitoring Phase...31

Web Usability Inquiry...32

3.1 Contextual inquiry ...32

3.2 Ethnographic Study...33

3.3 Diary Method...34

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Table of Contents

3.4 Interviews and Focus Groups ...35

3.5 Surveys ...36

3.6 Questionnaires...36

Web Usability Testing ...38

4.1 Thinking Aloud ...42

4.2 Co-Discovery ...43

4.3 Question-asking ...43

4.4 Performance Measurement...44

4.5 Server Log Analysis ...44

4.6 Activity recording ...47

4.7 Remote Testing ...48

Web Usability Inspection ...49

5.1 Heuristic Evaluation ...51

5.2 Heuristic Estimation ...54

5.3 Cognitive Walkthrough...54

5.4 Pluralistic Walkthroughs ...56

5.5 Feature Inspection ...56

5.6 Consistency Inspections ...57

5.7 Standards Inspections ...58

5.8 Formal Usability Inspections ...60

5.9 Guideline Checklists ...61

Open Issues...63

6.1 Laboratory or Real World?...64

6.2 Discount Approaches ...65

6.2.1 Discount Usability Testing ...66

6.2.2 Common Sense Approach...68

6.3 How Many Users Are Enough?...69

6.4 Different Methods for Different Media...71

Remote Web Usability Testing ...73

7.1 Advantages ...76

7.2 Efficacy ...76

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Table of Contents

7.3 Testing Approaches ...77

7.3.1 Client Application...77

7.3.2 Web Site ...80

7.3.3 Proxy...81

7.4 Effectiveness...82

7.5 State of the Art ...83

OpenWebSurvey...87

8.1 Testing Interface...87

8.1.1 Questionnaire Area...88

8.1.2 Test area ...89

8.2 Architecture ...90

8.3 Questionnaire Administrator ...91

8.4 Task logger...93

8.5 Test Analyser...95

8.6 The Prototype ...96

8.7 Comparison...99

On Road Usability Analysis... 103

9.1 Methodology... 103

9.2 Usability Inspection... 104

9.3 Usability Testing ... 108

9.4 Results ... 114

9.4.1 Equipment... 114

9.4.2 Timing ... 115

9.4.3 Navigation tasks... 115

9.4.4 Placement of information tasks ... 117

9.4.5 Information Retrieval tasks... 119

9.5 Overall Conclusions ... 122

9.6 Reported problems ... 123

Conclusions ... 124

References... 127

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Introduction

Introduction

"To some extent, usability is a narrow concern compared to the larger issue of system acceptability, which basically is the question of whether the system is good enough to satisfy all the needs and requirements of the users and other potential stakeholders […]"

(Nielsen, 1993)

Usability is a wide research field that involves researchers from different perspective and disciplines such as Communication Science, Computer Science, Engineering, Psychology, Anthropology, Sociology, Ergonomics, Human Computer Interaction, Marketing and Medicine.

As usability can be defined as the satisfaction of the users in achieving desired goals while using a product or a system, the concept can be applied to different fields, such as traditional product specification and development, user interface development, web site design and implementation.

The usability of a product or of a system can be evaluated using several techniques and methodologies that allow to gather data about how the user uses it and to interpret them and eventually suggest solutions to mitigate existent problems.

If we consider a web site as a web site that interacts with the users, it is possible to use traditional usability evaluation methods to evaluate its usability and to improve it.Web usability is not simply applying classical usability evaluation techniques to a new context, but tries to combine and

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Introduction

reuse effective traditional methods to test a new artefact that is characterized by specific target users and modalities of interaction.

As the World Wide Web is becoming wider day by day, it is very important that a user can access its information and can control it, knowing where is it, how to retrieve and access it: this attention on the user needs has conveyed the importance of having an usable and accessible web site.

Often web sites are targeted to a wide range of users, heterogeneous and geographically dispersed, with very different background and interests. It is then very important that these web sites could be accessible (and in some situations it is mandatory, as for public administration sites in European countries) by everyone in a variety of contexts, regardless of disability. In the opinion of the author, web usability implies web accessibility.

The purpose of this dissertation is to firstly discuss literature in the area of usability evaluation and to demonstrate how and when are suitable for web usability analysis. After a review of the different approaches that can be used for a usability evaluation, the dissertation introduces the remote web usability testing approach, which has been implemented in a prototype.

In Chapter I we will analyse the concept of usability, trying to identify its historical roots in different disciplines and to outline its importance in the life cycle of a product. Chapter II will focus on web usability, outlining the

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Introduction

differences between the usability evaluation of a products and the usability evaluation of a web site.

Chapters III, IV and V will discuss different approaches for web usability testing. Chapter VI will discuss some open issues regarding web usability.

Chapter VII will analyse remote web usability testing, Chapter VIII will discuss our prototype for remote web usability testing and Chapter IX will focus on the usability analysis of an Italian web site.

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Usability Culture

C h a p t e r I

I now wish to turn to workers in whom certain morbid affections gradually arise from some particular posture of the limbs or unnatural movements of the body called for while they work.

Bernardino Ramazzini, 1713

Usability Culture

In this chapter we will try to analyse the generic concept of usability and its history. Different definitions of usability have been proposed in the literature, but no one is widely accepted. As more talented researchers have been working for long time at that, we will not try to find a new, "best"

definition of usability, while we will try to compare some of the existing definitions and to see which aspects they are stressing more:

• "The ease with which an user can learn to operate, prepare inputs for, and interpret outputs of a system or component." (IEEE 90).

• "The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use." (ISO 9241).

• "The usability of an interface is a measure of the effectiveness, efficiency and satisfaction with which specified users can achieve specified goals in a particular environment with that interface." (ISO 13407).

The first definition stresses the "easy of use" of a system and the actions that should be easily performed (operating with a system, preparing input, interpreting output).

The second definition is interesting because adds the idea that usability is not a generic concept, but that it is specific to individual users and

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Usability Culture

contexts. Moreover, it is not restricted to the "easy of use", but clarifies that the goals for which a product is used have to be achieved with effectiveness, efficiency and satisfaction.

The third definition is very similar to the second, but stresses that usability is a measure of a condition, not a static property of an artefact.

In the writer’s opinion, while all the definitions correctly relate usability with user behaviour (easiness in the first definition, effectiveness, efficiency and satisfaction in the others) the second and third definitions better capture the complexity of the usability concept.

In this work, we will refer to usability as defined in the ISO 13407 definition, and in the next pages, we will introduce practical meanings and applications of it.

1.1 What Usability Means

Everyday products and objects exist in function of their users: hence, it is necessary to understand how the users use products, why they use particular produc ts and if their experience is satisfactory.

The ISO 9241 and ISO 13407 definitions of usability rightly focus on three main aspects:

• Effectiveness: each user has a particular goal to achieve when using a product. Effectiveness measures if the expected goals have been achieved and how, and measures the accuracy and completeness of the specified goals.

• Efficiency: measures the effort necessary to achieve the user’s goal and if it is proportionate to the expected result.

• Satisfaction: measures the pleasantness of using a particular product and if the product is suitable or not for the desired goal.

While the very first, precocious interests in the usability field in the modern times where usually related to work environment, nowadays usability is

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Usability Culture

considered relevant for everyday life. Many everyday products have been designed without thinking to the users, to their goals and to the context in which they should be used.

In a popular book, Norman (1998) analyses some daily used products and finds out how much unusable are they.

Norman states that the way systems and objects are understood by persons is based on:

• Affordances: the properties of an object that are immediately seen by an user and that convey how that object can be used. Many objects allow people understanding how to use them simply by looking at them, without the need of further instructions.

• Constraints: properties of an object that limit the way it can be used.

• Mappings: relationships between the controls and their immediate effects.

• Visibility: immediate visibility of the controls.

• Feedback: provision of information to the user on what is happening and on the effects of an action.

Norman defines this a "conceptual model" that allows people to predict the effects of their action.

Another issue that can improve usability of object is convention.

Conventions are widespread ideas that everyone can easily understand.

Since they are very general and (or) they are easily understood, products designers should try to follow conventions: in most cases is not worth trying to establish a new symbol when well known and working conventional symbols already exists.

For instance, the shopping cart symbol used in most e-commerce web sites is a clarifying example of the role of convention. Although the symbol was not as general and widely know as it should have been (Norman

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Usability Culture

reports that in several nations shopping carts are not so common), it has been used so long in web sites that changing the conventional symbol to adopt a new one, even if more widely used or understood, can be more problematic than keeping the current one.

Analysing usability more in depth than in the previous definitions, a system, or an object can be defined usable if it is:

• effective: people are able to reach their personal goals when using it;

• efficient: people are able to reach their goals with a minimal effort;

• engaging: the experience of use is satisfying and pleasant;

• error tolerant: the interface is able to recover user errors or to prevent them;

• easy to learn: both the initial and advanced tasks are easily performed without an hard trial learning;

• coherent: the interface is coherent with the existing conventions.

Product designers should focus their attention on users, thinking to the final users, to the interaction scenarios, to the users expectances and aims in using the product.

Interaction scenarios can be defined as descriptions of the context of interaction with the product, including user’s personal goals and expectances.

It is important to consider that a product is usable in function of the context in which it is used. The characteristics of the context may influence the usability of a product: usability is an overall system.

Users of the same product with different cultural backgrounds can have different perceptions of usability: typically, Japanese users are more tolerant of complex interfaces than European ones.

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Usability Culture

In the following paragraphs we will try to analyse usability historical roots in different disciplines.

1.2 Usability roots

While it can be difficult to find the "first" usability study we can find interests in usability that can be dated at least to classic authors.

In fact usability can be related to Ergonomics, Human Factors and Human Computer Interaction studies, as these disciplines take into account the interaction between the human and the artefacts.

1.2.1 Ergonomics

We can define Ergonomics as the study of the design and arrangement of equipments so that people can interact with the equipments in healthy, comfortable, and efficient manner.

Ergonomic studies (and the word itself) are a relative new branch of science, but an overview of the historical precursors can show how the interest on the subject has ancient roots.

Greek and Roman authors were already aware of the problems related to Ergonomics, but we cannot find a systematic exposition of the issues.

The environment and its relation to worker health were recognized as early as the fourth century BC when Hippocrates noticed lead toxicity in the mining industry. In the first century AD, Pliny the Elder perceived health risks for people working with zinc and sulphur. He devised a face mask made from an animal bladder to protect workers from exposure to dust and lead fumes. In the second century AD, Galen accurately described the pathology of lead poisoning and recognized the hazardous exposures of copper miners to acid mists.

In the Middle Ages, guilds worked at assisting sick workers and their families. In 1556, Agricola advanced the science of industrial hygiene even further when, in his book De Re Metallica, he described the diseases of

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Usability Culture

miners and prescribed preventive measures. The book included suggestions for mine ventilation and worker protection, discussed mining accidents, and described diseases associated with mining occupations such as silicosis.

The first systematic study in the Ergonomics field was held by Bernardino Ramazzini (1633-1714), commonly recognized as the father of work studies.

It is not known when Ramazzini commenced to work on his "De morbis artificum diatribe" (Diseases of Workers), but it is known that he lectured on this topic as early as in 1690. Published in 1700, this is the first comprehensive work on occupational diseases, and a milestone in the history of occupational medicine.

"De morbis artificum diatribe" outlined the health hazards of irritating chemicals, dust, metals, and other abrasive agents encountered by workers in 52 occupations. Among them were miners, potters, masons, wrestlers, farmers, nurses, soldiers, and many others. He even discussed the topic of overtaxed minds among "learned men". In discussing the aetiology, treatment, and prevention of these diseases Ramazzini often went back to Hippocrates, Celsus, and Galen, and, after summarizing their observations, related his own experience with the various diseases.

Three centuries in advance from ergonomic studies, he already pointed out the causes of workers illness.

"Two are, in my opinion, the causes that lead to the several and serious diseases of the workers. Diseases provoked from that same job that would have to give they the bread. The first cause, the more important, is represented from the property of the employed

substances, that produce gas and toxic powders and induce

particular diseases; the second one is represented from those violent movements and those not natural attitudes for which the same

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Usability Culture

structure of the body turns out vitiated, so that with the time serious diseases arrive."

Similarly, it is interesting reading his description of the illnesses connected to clerical work:

"The maladies that affect the clerks arise from three causes: first, constant sitting; secondly, incessant movement of the hand and always in the same direction; and thirdly, the strain on the mind . . ."

This three hundred years old description still fits well and describes with precision the unhealthy condition of workers using computer terminals.

1.2.2 Human Factors

Different definitions of human factors have been proposed by researches.

The following are some definitions that capture different aspects1.

• "Human factors are the discipline that tries to optimise the relationship between the technology and the human" (Kantowitz and Sorkin, 1983).

• "The central approach of human factors is the application of relevant information about human characteristics and behaviour to the design of objects, facilities, and environments that people uses "

(Grandjean, 1980).

• "Human factors discovers and applies information about human behaviour, abilities, limitations, and other characteristics to the design of tools, machines, systems, tasks, jobs, and environments for productive, safe, comfortable, and effective human use "

(Chapanis, 1985).

1 Quotes were retrieved from http://webword.com/whatishumanfactors.html on August 1 2003.

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Usability Culture

• "The goal of human factors is to apply knowledge in designing systems that work, accommodating the limits of human performance and exploring the advantages of the human operator in the process" (Wickens, 1984).

Human factors go well beyond what these definitions. Human factors are a data-based, rigorous discipline with practitioners from a variety of backgrounds doing all kinds of works and making products, systems, and web sites easier to use and easier to learn.

1.2.3 Human Computer Interaction

The term "Human Computer Interaction" (HCI) is commonly intended interchangeable with terms as "Man Machine Interaction" (MMI),

"Computer Human Interaction" (CHI) and "Human Machine Interaction"

(HMI).

In the Association for Computing Machinery (ACM) web site (http://sigchi.org/cdg/) we can find a satisfying working definition of Human Computer Interaction:

"Human-Computer Interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them."

Human Computer Interaction is an interdisciplinary area, that is emerging as a specialty concern within several disciplines, each with different emphases: computer science (application design and engineering of human interfaces), psychology (application of theories of cognitive processes and the empirical analysis of user behaviour), sociology and anthropology (interactions between technology, work, and organization), and industrial design (interactive products).

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Usability Culture

Regardless of the chosen definition of computer science, HCI is clearly to be included as a part of it and is as much a part of computer science as it is a part of any other discipline.

If, for example, we adopt Newell, Perlis, and Simon's (1967) definition of computer science as "the study of computers and the major phenomena that surround them" then the interaction of people and computers and the uses of computers are certainly parts of those phe nomena. If, on the other hand, we take the recent ACM (Denning et al., 1988) report's definition as

"the systematic study of algorithmic processes that describe and transform information: their theory, analysis, design, efficiency, implementation, and application" then those algorithmic processes clearly include interaction with users just as they include interaction with other computers over networks.

Because Human Computer Interaction studies an human and a machine in communication, it draws from supporting knowledge on both the machine and the human side. On the machine side, techniques in computer graphics, operating systems, programming languages, and development environments are relevant. On the human side, communication theory, graphic and industrial design disciplines, linguistics, social sciences, cognitive psychology, and human performance are relevant. In addition, of course, engineering and design methods are relevant.

A related set of developments were attempts to pursue "man-machine symbiosis" (Licklider, 1960), the "augmentation of human intellect"

(Engelbart, 1963), and the "Dynabook" (Kay and Goldberg, 1977). Several building blocks for Human Computer Interaction come out of this line of development. Some of these building blocks include the mouse, bitmapped displays, personal computers, windows, the desktop metaphor, and point-and-click editors (Baecker and Buxton, 1987).

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Usability Culture

According to Booth (1989), although computer technology has made great advances over the past 40 years, the designer’s knowledge and understanding of the user has not significatively changed.

Human Computer Interaction is today an important research issue, as, according to designers and developers are no longer representative of most users. The users [of computer systems] are no longer mainly computer professionals, but are mostly discretionary users. As a result, the designers are no longer typical of or equivalent to users; but the designers may not realize just how unique and therefore how unrepresentative they are.

1.3 Return of Investment

Market researches from different sources state that a poor usability of the used and/or produced products can be very expensive for a company.

Landauer (1996) states that "the average software program has 40 design flaws that impair employees’ ability to use it. The cost in lost productivity is up to 720%".

If an employee does not understand how to use a product or how to use it efficiently, the productivity can decrease and there can be higher error rates and risks of damages. Moreover, the inability to use a product can generate anger and frustration in the employer, and then reduce her confidence and moral.

A company producing non-usable products has to face up increasing costs for customer care, since customer will not be able to use the products and obviously will ask the producer for assistance. As en example, during 1992, in order to meet its customer support call needs, WordPerfect had to employ over 900 customer response specialists.

A non-usable product can discourage clients from buying it, or from buying newer versions, decreasing the value of the corporate brand and the

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Usability Culture

increasing productivity and customer loyalty. Design changes due to usability work at IBM resulted in an average reduction of 9.6 minutes per task, saving $6.8 million in the first year (Karat, 1990).

Obviously, an usable product increases productivity as an employee can exploit it to full advantage, using advanced features and the company does not need to sustain high costs for training and support if products are easy to use.

1.4 Design

Often product designers are not typical users of their products and therefore they design considering more aesthetics and innovation then the usability of the products. Human-centred design focuses on the active involvement of the users in the design process or on a previous understanding of user requirements and context of interaction.

In the past years, many usability researchers have been pointing out the problem of "cool" but non-friendly interfaces.

Recently Donald Norman has been supporting a very interesting and promising point of view, that he calls "theory of emotions" (2003).

According to this theory user behaviour depends both from reflections and from emotions: "attractive items work better... they put you in a good mood". For example, using a nice car that increases self-esteem puts you in a good mood: driving looks better and everything seems simpler.

Similarly, if you are eating a very well presented nouvelle cousine or japans dish, you will likely think that it is good, even before trying it:

emotions, in this case aesthetic appeal, influence your judgement. Norman supports this theory with a personal example. Around 20 years ago, when he was using a compute r with black and white monitor, he was asked to use a colour monitor for a test: after a week of using it, he realized that it added no value, but that he would not give it up!

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Usability Culture

1.5 Legislation and Guidelines

Even if the potential marketing benefits are now clear and recognized, often usability is not considered part of product specifications, as it is very hard to evaluate and measure it.

In Europe, an European Council directive (90/270/EEC), transposed into national law in every European country, obliges emplo yers to adopt software "easy to use", that embodies "the principles of software ergonomics". The law requires the customer of a software product, who is in the role of an employer, to prevent users from undue burden, which may cause health hazard or mental strain.

The key requirement runs as follows: "the principles of software ergonomics must be applied...". This holds for the development of products, for selecting, purchasing or adapting them.

In Italy, current legislation on usability (AIPA/CR/32) applies only to Public Administrations and states that their web sites must be accessible even from individuals with physical or sensory affections, or using instruments with limited performances or in unfavourable environmental conditions.

Moreover, it underlines that, as electronic documents are more accessible compared to papery documents because of the use of new multimodal technologies that can translate them to different perceptive modalities, the exclusion caused by communication barriers is particularly grievous.

In 1994 (SO 9241-11 was published to guarantee a common understanding of what constitutes usability and how it could be measured and specified. The main idea of this guidance is to represent usability as a set of properties, features and attributes needed to make a product usable and then to measure if these properties are implemented in the final product.

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Usability Culture

The main characteristic recognized by ISO 9241-10 were suitability for the task, suitability for learning, suitability for individualisation, conformity with user expectations, self descriptiveness, controllability, and error tolerance.

Besides ISO 9241-10, other specific guidelines for the design of usable interface have been published. One of the most famous are the Menu Dialogue Guidelines published in ISO 9241-14, that present 112 recommendations for creating usable menus.

In addition, software companies published guidelines on designing usable interfaces, as IBM Common User Access Guidelines (IBM Corporation, 1993) or Microsoft Windows Interface Design Guide (Microsoft Corporation, 1995).

The main disadvantage in guidelines is that often they are very specific to a particular product and it is very hard to evaluate their application.

Moreover, even if a designer follows exactly some guidelines, it is not certain that the resulting product will be usable.

1.6

Usability and Information Technology

Obviously, usability has emerged as a core issue in Information Technology products and services. Usually this kind of products, systems and services are characterized by an innovative technology and often they can be very difficult to use, especially for non-skilled users.

As nowadays computer technologies are widespread adopted and have become mass products, it is very important to study their design in order to be usable by each user.

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Web Usability

C h a p t e r I I

Web Usability

Web usability, that it is the study of usability applied to the web, arose as research field at the very beginning of the Internet era. The Internet as we intend it today (the Word Wide Web), were users connected to the network can access data on remote servers, has been developed at CERN, Switzerland, starting from 1989, when Tim Berners Lee wrote a draft called "HyperText and the CERN". The availability of CERN's files using the Internet was announced in the Usenet newsgroup, alt.hypertext, in August 1991.

The term "surfing the Internet" was firstly used in a written publication by Jean Armour Polly in June 1992, and by the end of the year, there were 50 web servers (Gribble, 2003) and 1,000,000 of hosts only. The term

"Internet" was formally defined in October 1995; nevertheless Nielsen wrote his first article on web usability in May 1995, and looking in the newsgroup archives at groups.google.com we can find a promotional message2 of a company, dated December 1995, offering consulting services on usability.

According to Nielsen "usability is the measure of the quality of the user experience when interacting with something" (1998).In a web context the quality of user experience can be determined by several aspects, as ease of learning, efficiency of use, memorability, minimization and prevention of errors, satisfaction, and accessibility.

Actually, as most researches demonstrate, the web is not enough usable and it provides a very active work field.

2 http://groups.google.co.uk/groups?hl=en&lr=&ie=UTF -8&oe=UTF- 8&group=alt.comp.shareware

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Web Usability

In 2001 a research (Spool et al.) on web site usability discovered that users could only find the information they needed 42% of the time, even if they were taken to the right page by an administrator. Another research of 1998 performed by Zona Research Inc (Dey, 2003) on 239 long time Internet users, stated that 1 out of 3 users find "somewhat or extremely difficult" to locate specific products on web sites and that 62% percent of them gave up looking on at least one occasion in the last two months.

More recently, in 2001, a research on the main dot.com crashes reported that web usability was one of the major problems:

"Too many options, unclear navigation, badly laid out information, and purchase or checkout process that was just too difficult to use"

(Australian net Guide, 2001)

Human Computer Interaction studies have evolved in considering web usability a major field and researchers have started to study user behaviour while surfing the web, performing usability tests in order to understand the main problems and difficulties.

2.1 Web Accessibility

The World Wide Web was conceived in a scientific environment to be used by scientists. The original form of the HyperText Markup Language (HTML), the language used to build web pages, was structured around headings, paragraphs and other structures that define the information content of a textual document.

Presentation was a secondary concern.

As the Internet grew and people other than scientists began to access the web, new professional figures, in charge of developing web pages, appeared. The focus was no more on content, but on presentation (see Figure 1): web pages started to be more appealing and rich of graphics.

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Web Usability

Figure 1 – Focus on content and focus on presentation compared

Techniques used included:

• proprietary browser-specific HTML extensions for adding formatting properties;

• using images with fancy fonts for rendering text to replace plain text on the page;

• using images to create graphical elements for presentation, such as fancy borders around the page;

• using data tables for page layout structures, often with blank images to control the white space;

• using plugins or scripting to produce additional effects not provided by HTML.

This approach is characterised by several and severe drawbacks. For what regards web usability, it caused web sites to be not accessible, that means difficult or impossible to be visited by people with accessibility limitations.

Quoting World Wide Web Consortium (W3C), the authority responsible for establishing standards for the web, "web accessibility means access to the

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Web Usability

Web by everyone, regardless of disability". In the following pages we will discuss what is web accessibility, why is web accessibility so important and what is possible to do to make web experience accessible.

Before going on, we stress here that accessibility issues are strictly part of usability research, as they deal with effectiveness, efficiency and satisfaction of specified users while achieve specified goals, that was the definition of usability we have adopted. Hence, a web site that is not accessible cannot be usable for a wide range of population as well.

Web accessibility has become an important issue since the use of the web has spread rapidly into all areas of society and therefore there are millions of people with different kinds of disabilities that have access to the web.

Unfortunately, web sites often provide technological or interface barriers that inhibit the access to these people. Among the various kinds of disabilities that can affect the access to the web, we have:

• hearing disabilities, like deaf, hard-to-hearing or hearing-impaired persons;

• visual disabilities, like blind, colour-blind or visually-impaired persons;

• mobility disabilities, like physical disabled or motor skill impaired persons;

• learning disabilities, like dyslexic persons.

It has been estimated that between 15% and 30% of world population, and almost 10% of internet users, has some kind of disability (Waddell et al., 2003).

We should also consider that the average age of population in many countries is increasing and that the aging process sometimes impairs person’s abilities.

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Web Usability

As the web is becoming a key resource for information, commerce, entertainment, distance learning, job searching, government services and as it is often displacing traditional sources of information, it becomes more important that everyone could access to information.

In fact, web accessibility means to provide and equivalent and effective access to communication sources to everyone, without altering the sources or without imposing hardship to the users.

We have to stress that making web experience accessible implies:

• accessible web sites and web applications, that people with disabilities can perceive, understand, navigate, and interact with;

• accessible web browsers and web applications in general (as rich media players), that can be used effectively by people with disabilities, and that work well with assistive technologies that some people with disabilities uses to access the Web;

• accessible web authoring tools, which support production of accessible Web content and web sites, and that can be used effectively by people with disabilities.

It should be considered that each user has different preferences and habits, as well as disabled persons. It is then important to allow the user controlling the display of the information, not imposing the "look and feel"

of a web site to the user.

To achieve these goals a designer should:

• Design for different browsers: there are many widely spread browsers and not all support the same commands. An accessible web site should be at least visible by every web browser.

• Follow standards: if a designer follows the standard of the language that she is using, it is more probable that the web site will be visible on different browsers and platforms.

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Web Usability

2.1.1 Examples of Web Accessibility

As stated before, the main categories of disabilities that affect persons are four. Each one affects in a different way the access to web sites.

Hearing-impaired persons have difficulties in hearing sounds, hence every audio sound should be captioned or provided of a text equivalent description.

Visually impaired users may have difficulties in seeing images or in reading small text. It is then important to use relative font size (so that the user could change the font dimension according to her needs), to avoid small text, poor colour contrast and excessive graphical images. It should always be considered to not rely on a single one communication channel (e.g., sounds, images or colours) to convey information, in particular when information is relevant or critical. When communicating something with images, it is important to always provide an alternative description, so that even disabled users could understand the meaning of the message. In HTML, there is a way to provide an alternative description for images that will be shown in standard browsers as a tool tip when passing the mouse over the image, while a screen reader tool (usually used by blind persons) can read the alternative description.

Persons with mobility disabilities often use specialized hardware for input, so web site should be designed to be accessible not only with the mouse but also with the keyboard or similar devices.

Cognitively impaired users have often problems in reading web pages, so they benefit from well structured and from clearly written web pages.

2.1.2 Web Usability and Web Accessibilit y

The main difference between web usability and web accessibility is that usability problems affect all users equally, independently from their abilities or disabilities, while accessibility problems affect mostly persons with disabilities. This means that if there are accessibility problems a

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Web Usability

person with disabilities is disadvantaged with respect to a person without a disability.

Accessibility can then be considered as a sub sample of usability, since both affect the access to web sites.

2.1.3 Design for All

Accessible web design contributes to better design for other users.

It is not as strange as it seems. Attention to disability usually implies (but does not limit to) attention to ergonomic design, which can advantage most users. In fact, accessibility contributes to maximize the ability of all users to access information, services, and resources.

The practice of designing accessible interface has been defined as Universal Design (Design for All)

"Universal design is the process of creating products (devices, environments, systems, and processes) which are usable by people with the widest possible range of abilities, operating within the widest possible range of situations (environments, conditions, and

circumstances), as is commercially practical."

(Vanderheiden, 2000)

Designing an universal web site using existing standards and web technologies can produce positive externalities for all users:

• Adopting multimodal interfaces (interfaces that are accessible through different sensorial channels, as visual, auditory, tactile ones) provides benefits for users with mobile devices. In fact, mobile devices are characterized by small displays, low bandwidth, noisy environment and a multimodal interface can improve the interaction. Moreover there are situations in which only the use of multimodal interfaces allows the interaction with the devices, such

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Web Usability

as in-vehicle systems, that allow the user interacting with them while driving.

• Providing redundant text/audio/video equivalents allows supporting different learning styles, low literacy levels, and second-language access.

• Adopting stylesheet technology allows reducing the dimension of transferred web page, increasing the download speed and provides better performance and an higher possibility of personalization.

• Providing an alternative caption for audio sounds allows a better indexing of the content of the web page (useful especially for search engines) and a faster searching of the content.

Nielsen (2001) suggests that disabled users are simply persons who "have jobs to perform and goals to accomplish" while accessing a web site. For this reason a web site should not only be technically accessible to everyone but should also allow everyone accessing its content and should support the execution of tasks.

The Nielsen group recently (2001) performed an usability test on 19 web sites, with 84 disabled users who were blind or had visual or motor impairments.

They asked them to perform several tasks, such as buying a CD, or retrieving information about bus time scheduling, or searching for the best mutual fund. The test was also administrated to a control group of 20 users without disabilities.

The results of the test were that the success rate in performing the test for the control group was three times better than the success rate for the users with disabilities.

Achieving web accessibility should then be considered as a way to provide equal opportunities and to avoid discriminations.

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Web Usability

2.1.4 Guidelines for Accessibility

Recently W3C published several guidelines about web accessibility that play a critical role in making the web accessible, by explaining:

• how to create accessible web sites (Web Content Accessibility Guidelines 1.0 - WCAG);

• how to design software that supports production of accessible web sites (Authoring Tool Accessibility Guidelines 1.0 - ATAG 1.0);

• how to design accessible browsers and authoring tools (User Agent Accessibility Guidelines 1.0 - UAAG 1.0).

The Web Content Accessibility Guidelines 1.0 were developed in 1999 by the Web Content Accessibility Guidelines Working Group inside W3C.

They focus on how to make accessible web sites providing general guidelines. They propose three priority levels of normative checkpoints and provide several supporting resources.

The Authoring Tool Accessibility Guidelines 1.0 were developed in 2000 by the Authoring Tool Accessibility Guidelines Working Group. They focus mostly on the requirements for authoring tools for the web (e.g., programming or image editors, conversion tools) to generate an accessible code. Moreover, they suggest how to realize accessible authoring software.

The User Agent Accessibility Guidelines 1.0 (UAAG 1.0) were developed in 2000 by the User Agent Accessibility Guidelines Working Group. They focus on the realization of accessible applications for accessing web sites and their content, like multimedia players and browsers. Actually, a new working group inside W3C (Evaluation and Repair Tools Working Group) is developing some Techniques for Accessibility Evaluation and Repair. In particular, this group maintains a reference list of tools to evaluate and repair accessibility.

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Web Usability

2.1.5 Accessible Web Sites

The main suggestion of these guidelines is to realize pages that transform gracefully and that can be adapted to different devices.

Accessible web pages should:

• Provide equivalent alternatives to auditory and visual content, which is providing always an alternative textual description, which can be rendered in way accessible to almost every user.

• Do not rely on colour alone, but ensure that the content is understandable even if the page is seen without colours.

• Use markup and stylesheets properly, keeping the style separated from the content.

• Clarify natural language usage, that is explicitate which language is used in the document and how the abbreviations have to be expanded, in order to facilitate multilingual access.

• Create tables that transform gracefully, that are using the appropriate markup to communicate to the user agent which is the structure of the table and how to navigate it.

• Ensure that pages featuring new techno logies transform gracefully and can be seen even if the new technologies are not available.

• Ensure user control of time-sensitive content changes, providing a way to stop the moving, blinking, scrolling, or auto-updating of objects and pages.

• Ensure direct accessibility of embedded user interfaces, allowing every user to access to the interface of a specific object (as the interface of a media player used to play a video file) or to have an equivalent accessible interface.

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Web Usability

• Design for device-independence, enabling the activation of page elements through different input devices.

• Use interim solutions, to ensure backward compatibility with older browsers and user agents.

• Use W3C technologies and guidelines, following the standards.

• Provide context and orientation information, to help people understand how the elements of a page are grouped and which is the relationship between them.

• Provide clear navigation mechanisms to ensure that people can easily find what they are looking for.

• Ensure that documents are clear, with a simple and consistent language, layout and graphics.

It is easy to see that many of the accessibility features required by UAAG 1.0 also improve usability for many other individuals.

For instance, keyboard operation of the user agent benefits some users with visual and physical disabilities, but also benefits users who prefer keyboard access (e.g., expert users). UAAG 1.0 requirements are expected to benefit users with slow Internet connections, as well as users who use their computer in a situation where their hands, ears, or eyes may be busy with other activities.

2.2 Web Usability Studies

As usability evaluation is becoming increasingly important in the web design process, several different usability evaluation methods and techniques have been developed to understand if, in a given context of use, a web site allows the users to use it to achieve their goals in an effective way.

First of all it is useful to analyse how the usability methods can be applied in the different phases of the design process that, as stated by Dix et al

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Web Usability

(1998) and Nielsen (1993) consists of iterative cycles of designing, prototyping and evaluating.

We decided to adopt Helander et al. (1993) classification of usability design phases and to adapt it to the web site life cycle: for every phase of the design process it is possible to identify which classical usability

evaluation methods are more suitable and why.

We will refer to the different usability methods as "usability analysis approaches" (or methods) and we will group them in three mayor families:

usability testing, usability inspection, and usability inquiry.

Usability analysis approaches have been grouped in several ways by different authors but, up to our knowledge, there are no works on specific categorization of web usability analysis approaches. While many of the approaches that can be used to analyse the usability of artefacts can be used to analyse web sites, in the following chapters we will analyse the peculiarities of web usability analysis.

We will describe usability approaches separately, but most researchers agree that not only there is not a "best practice" available for all situations, but even that in many cases using different approaches in different parts of the usability study can be a key factor to the success.

In the following chapters, we will try to identify the main advantages and disadvantages of some of the approaches and then we will present a state of the art of web usability studies.

2.3 Usability Design Phases

Adapting Helander et al. (1993) usability design phases, we can distinguish four main web usability phases in the development of a web site:

• gearing-up;

• initial design;

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• iterative development;

• system monitoring.

Looking at Figure 2 you can see that design is intended as a linear process that includes iterative phases, and not as a totally iterative process, as it is intended, among others, by Perlman (1993). Perlman intends usability design as an iterative process of evaluation, design, implementation.

In the author point of view, evaluation, design and implementation can be part of different phases of the design process, but they are qualitatively different. For example, the evaluation done in the gearing up phase is qualitatively different from the kind of evaluation that can be done in different phases of the process, as in the system monitoring.

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Web Usability

Figure 2 – Usability design phases

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Web Usability

2.3.1 Gearing Up Phase

Gearing up phase is mainly an information gathering and conceptualisation phase, were people involved in a projects looks for starting points (as related systems) and decides system characteristics, basing on project-specific business strategies.

In this phase the project team familiarises with recognised standards and guidelines and with development procedures the organisation may have.

2.3.2 Initial Design Phase

Initial design phase is when people involved in the project makes preliminary specification of the user interface, basing (when appropriate) on existing and leading systems, standard and guidelines, user needs.

Early focus on users take centre stage here. According to Helander,

"integrated design, in which all aspects of usability are considered at the outset and evolve together, begins in this phase".

2.3.3 Iterative Development Phase

Iterative development phase is when the project is iteratively tested by users and developers, and when relevant issues appear, the project is adapted to users’ feedback.

2.3.4 System Monitoring Phase

System monitoring phase is when the project has been shipped and the team concentrates on usability issues that appear in the live web site.

Usability issues that did not appear in the test site used in the previous phases could appear now, when the system is on-line, and in this case the project could return to an iterative development phase.

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Web Usability Inquiry

C h a p t e r I I I

Web Usability Inquiry

Web usability inquiry is a set of methods used by usability evaluators to proceed "from the native point of view", obtaining information about users' likes, dislikes, needs, and understanding of the system, by talking to them, observing them using the system in a real working situation, or letting them answer questions verbally or in written form.

The following table summarizes when the different methods (that will be described in the following pages) should be applied with respect to the design phases as outlined in Chapter 2.3 .

Gearing-up Initial design

Iterative development

System monitoring Contextual

inquiry X

Ethnographic

Study X

Diary Methods X X

Interviews and

focus groups X X X X

Surveys X X

Questionnaires

X X

Table 1 - Web usability inquiry methods: development phases

3.1 Contextual inquiry

Contextual inquiry is a structured field interviewing method, based on some core principles that differentiate this method from plain, journalistic

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Web Usability Inquiry

interviewing. Contextual inquiry is more a discovery process than an evaluative process; more like learning than testing.

Interviewing during a contextual inquiry study usually does not include set, broadly worded questions. Instead, the partnership between the interviewer and interviewee is used to create a dialogue, where the interviewer can not only determine the user's opinions and experiences using the web site, but also her motivations and context.

It is a long-term study, and it is one of the best methods to use when researchers need to understand the users' work context. It may sound like a cliché, but there really are people who print out web pages and mark it up with comments.

This approach is very useful in the early stages of development, for finding out about work practices in domains that researchers do not know.

3.2 Ethnographic Study

Observing users in the field is often the best way to determine their usability requirements. Traditional usability analysis, while providing a laboratory environment that makes easy the data collection and recording, also removes the user from her usual context. Sometimes, it is best to see exactly how things are done in the real world.

Adequate data collection is related to identifying as many artefacts and outcroppings as possible:

Artefacts are physical objects in use at a site (notebooks, forms, reports, spaces, walls)

Outcroppings are noticeable physical traits that mark or characterize the site (size of cubicles, size of whiteboards and what's written on them, uniforms written by certain castes of personnel). For example, in one hospital study, people who has to wear scrubs around the hospital had more status and influence

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Web Usability Inquiry

than those who could not, either by management decree or by peer pressure.

This technique is best used in the early stages of development, when the researcher needs to know more about the issues surrounding the use of a web site in a given situation (e.g., in a real work situation) and to gather user requirements and issues for incorporation into preliminary designs.

3.3 Diary Method

The diary method is proposed by Kangas, Sinisamml and Paihonen (2003), as an alternative when traditional usability analysis cannot be performed.

Kangas at al. distinguish four user-centred activities, that need to be taken into account in all the stages of product development: understanding and specifying the context of use, specifying user and organization requirements, producing design solutions and evaluating the design against requirements.

According to their assumptions, and according to the usability definition we are adopting, the characteristics of the context (users, tasks, environment) may be as important to determining usability as the characteristics of the web site itself.

Laboratory tests are biased toward how tasks are performed with the system, at the expense of what tasks can be performed; according to Kangas et al., they are less suitable in early stages of development process, where what the system can do is often the major design concern.

Two different kinds of diaries can be used: free form and structured.

Free form diaries allow persons to express themselves freely, but the time required to analyse their answers can be long.

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Web Usability Inquiry

Structured diaries, where a selection of questions and responses is provided, can reduce user expressiveness, but are easier to analyse and therefore are more useful for a large sample population.

When using the diary method, test users will access a prototype of the web site and a script of the tasks they have to perform in the site.

The kind of information that can be obtained from diaries includes what features that users have been using and how often, if they used the site at work or at home, and why.

The diary method, therefore, is best used when the researcher does not have the time or the resources to use user monitoring methods or when the level of detail provided by user monitoring methods is not needed.

Moreover, it is a good solution for testing web sites or web application for mobile users.

The main disadvantage of this technique is that there is no observer to see what the user is doing, the facial expressions of the user, or even the spoken comments inadvertently expressed during difficult tasks.

Unfortunately, the diary method cannot capture usability problems producing hesitation that, as Krug points out, are one of most important problems when interacting with web interfaces.

3.4 Interviews and Focus Groups

Interviews and focus groups let the researcher query users about their experiences and preferences. Both are formal, structured events where researchers and users directly interact.

Interviews and focus groups involve the presence of the researcher, to interact and facilitate discussion about the issues rose by the questions.

With multiple users present, as with focus groups, the interaction among the users may raise additional issues, or identify common problems that many persons experience.

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Web Usability Inquiry

This technique can be used at any stage of the development process, depending on the questions that are asked. Often, interviews or focus groups are used after web sites are shipped to assess customer satisfaction. More likely, though, interviews and focus groups are held at very early stages of development, when the web site requirements are still not firm. Focus groups are then held to extract user requirements prior to initial design.

When analysing web sites, participants for the focus groups and interviews can be recruited directly from the Internet, asking to the web site users to participate to the test.

3.5 Surveys

Surveys are ad hoc interviews with users, where a set list of questions is asked and the users' responses recorded. Surveys differ from questionnaires because they are interactive interviews, although not structured like contextual inquiries nor formally scheduled and organized like focus groups.

This technique can be used at any stage of development, depending on the questions that are asked in the survey. Often, surveys are used after products are shipped to assess customer satisfaction with the product.

Such surveys often identify usability issues that should have been caught in-house before the product was released to the market.

3.6 Questionnaires

Questionnaires are written lists of questions that the researcher distributes to test users. Questionnaires differ from surveys in that they are written lists, not ad hoc interviews, and require the users to fill out the questionnaire and return it back.

This technique can be used at any stage of development, depending on the questions that are asked in the questionnaire. Often, questionnaires

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Web Usability Inquiry

are used after products are shipped to assess customer satisfaction with the web site. Such questionnaires often identify usability issues that should have been caught in-house before the web site was released.

Questionnaires are often submitted remotely: they can be used to gather user answers and personal data without effort, or they can be used in conjunction with remote web usability testing tools, as we will describe in Chapter IX.

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Web Usability Testing

C h a p t e r I V

Web Usability Testing

Over the last few years the number of web sites and of Internet users has increased: Internet has become a mass medium.

Actually the Internet is plenty of web sites, some created for information purposes, others for marketing purposes, but all them need to attract users and distribute information or products.

The risk of building a non usable web site is the risk of losing users, with all the economical and ethical consequences that this may convey.

Consequently one of the main issues in creating a web site is how to make it usable for every typology of user. And, in general, the Internet users are characterized by different socio-cultural backgrounds and skills.

The methodologies proposed for web usability testing are strictly related to HCI and experimental psychology principles, and derive from approaches to traditional usability that can be found in the literature.

All these approaches share the same methodology structure, that can be split in different phases:

• define the testing purposes;

• define the objectives of the test;

• define the profile of test users;

• define the experimental design;

• define the tasks that the users should perform;

• specify the test apparatus;

• identify the required personnel;

• prepare the subject for the test.

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Web Usability Testing

First of all, it is necessary to know clearly which are the goals of the research, and to be able to translate them into a specification of objectives for the test.

Defining the testing purposes implies understanding which are the characteristics required for the web site and which are its functional requirements. Then it is possible to define in detail the goals of the research: a broad goal like "is this web site usable?" is not enough. The goals should be focused on the topics and issues that are relevant for the project.

To achieve this, it is very important to identify the target of the users to test, according to the testing purposes. The users can be novices, or experts, male or female, young or old, or belonging to different socio- cultural or ethnics groups.

One of the most debated issues in usability testing is the number of users to test to have relevant results, but this issue will be analysed in Chapter V.

The fourth phase regards how the test will be structured and conducted to eliminate non-interesting variables from the analysis.

Then there should be an accurate phase of design of the test, in which the researchers specify the tasks that the subjects will be asked to perform during the test. The definition of the tasks should be made considering which are the tasks the users normally perform when they are using the web site and which are the testing purposes. A task should be defined in terms of:

• actions to be performed;

• meaning of a completed task;

• meaning of a non-completed task.

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Web Usability Testing

The test scenario should also be considered, setting up all the instruments and aids that the subjects will need, paying attention to not distract or influence the users with instruments different from the usual ones. For example, using a "cool", new browser instead of a common one could not be a good idea.

According to the selected approach it is also important to decide how many and which kind of personnel is needed. If the test is a laboratory experiment, maybe a test administrator and one or more observer might be necessary as well.

Selecting the sample user between the population is a very difficult task, since it requires to decide the number of users necessary to represent the population with the correct mix of experience, skills, and demographic characteristics.

It is possible to recruit the subjects from fellow employees, from family and friends, to enlist temporary employment agencies and market research firms to get people, to put out an ad on the Internet, or in newspapers, to contact user groups and industry organizations. Of course it is easier to find the subjects if the target users belong to common user groups, while it could be harder to find particular user populations, such as blind persons belonging to a particular social cultural and ethnic group.

The last phase is very important as it regards the preparation of the subjects for the test. The subjects should be set at ease before performing the test, explaining them the organizational details and the purposes of the test, stressing that an usability test aims to evaluate a web site, not its user.

After completing the test, the data should be analysed to produce quantitative and qualitative results.

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Web Usability Testing

In this phase it is important to identify which are the major problems, to summarize the performance data, to evaluate them performing statistical analysis and then to summarize the preference data.

An ideal timeline for a web usability testing is to follow the life-cycle of the web site development: in the initial stages it is important to test the various versions of the web site, maybe against the competitor’s products to find out which are the major design issues. Then in the middle stages it is important to validate and refine the design, while in the later stages the purposes should be to verify that the web site meets the requirements and the functional specifications.

In the following sections, we will analyse the different techniques adopted for web usability testing, while the following table summarizes when the different methods should be applied with respect to the design phases outlined in Chapter 2.3 .

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Web Usability Testing

Gearing-up Initial design

Iterative development

System monitoring Thinking

aloud X X X X

Co-discovery

X X X X

Question

asking X X X X

Performance Measurement

X X X

Server log

analysis X

Activity

recording X X

Remote

testing X X

Table 2 - Web usability testing methods: development phases

4.1 Thinking Aloud

Thinking aloud is one of the most popular techniques adopted for web usability testing. It consists in the simulation of a web site surfing during which the participants are requested to perform several tasks and to freely express their thoughts, feelings and opinions.

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Web Usability Testing

This technique is ideal for understanding the subjective point of view of the user while approaching the interface, allowing the researcher to understand better the user’s mental model.

Moreover, this methodology allows to interact with the user and to know how she would describe the web site and the problems she has to face, and then, maybe, to use this terminology in the help section of the web site.

This approach is very popular also because it is not expensive and does not require complex instruments. A large amount of qualitative data can be gathered at a reasonable cost.

4.2 Co-Discovery

Co-discovery method is a cooperative method for investigating the usability of a web site. It requires two users to perform several tasks together while they are observed by a test observer that gathers the data.

The testing scenario is very similar to the thinking aloud approach, as it requires tasks to be performed but involves also a mutual help between the two participants. The cooperation is the main advantage of this approach with respect to thinking aloud: in fact, the interaction between the two participants allows them to bring out more insights than a single participant usually does.

This approach is useful during all the life cycle of the web site but can be adopted only if the web site under analysis is suitable to be visited in cooperation. Usually Internet web site are not developed to be visited in cooperation, while it is more common to visit in cooperation a corporate intranet web site.

4.3 Question-asking

Question asking approach can be considered as an evolution of the thinking aloud approach as it requires a test administrator to prompt

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