Candidate: Markel Vigo Echebarria Advisor: Julio Abascal González Donostia, November 23rd 2009.

Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement andAdaptation Perspective

Candidate: Markel Vigo EchebarriaAdvisor: Julio Abascal González

Donostia, November 23rd 2009

Putting in context About 10% of the world’s population lives with a

disability

The WWW is not accessible

Web accessibility guidelines

A number of motivations for a barrier free Web

Evidence shows “guidelines are not enough”

Interaction context has to be captured

Technological gap: automatic tools do not consider context

Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 2

Outline

1. Motivation

2. Web Accessibility Evaluation

3. Web Accessibility Measurement

3.1 Web Accessibility Quantitative Metric

3.2 Deploying accessibility scores in Search Engines

4. Contextual Web Accessibility Assessment

5. Device-tailored Accessibility Assessment

6. User-tailored Accessibility Assessment

7. Conclusions

Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective

Motivation Conformance to guidelines is a minimum requirement

for developing accessible sites

Evaluation is a key stage

Automatic tools help developers

A comprehensive assessment requires expert involvement

Again, “guidelines are not enough”

Hypothesis: “we include user’s interaction context in the assessment process of web accessibility, results will better capture user experience”


Outline

1. Motivation






5. Device-tailored Assessment

6. User-tailored Assessment

7. Conclusions


2. Web Accessibility Evaluation There are a number of accessibility guideline sets

- Focus on disability- Access devices- Application environment

A tool for coping with them requires- Evaluation engine independent of guidelines- A language to frame them

A set of guidelines has been studied to find patterns- General & desktop: WCAG 1.0, Section 508, IBM Accessibility

Guidelines- Mobile devices: Mobile Web Best Practices 1.o- Target group of users: Elderly [Kurniawan & Zaphiris, 2005]- Specific environments: IMS guidelines for accessible learning

applicationsAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 6

2. Web Accessibility Evaluation 21 patterns were found for XHTML test cases

- 6 require checking XHTML elements- 11 require element and attributes- 4 of them are complex relationships

The Unified Guidelines Language (UGL) has been defined- XML-Schema that frames all test cases- Expressive

For evaluation purposes UGL are transformed into XQuery- Each test case has a corresponding XQuery template


2. Web Accessibility Evaluation Test-case 17: “a specific value of an attribute requires another non-empty attribute ”

<label> </label><analysis_type>check attribute</analysis_type>

<related_attribute><atb> </atb> <analysis_type>value</analysis_type> <content test = “ ”> </content><related_attribute>

<atb> </atb><analysis_type>compulsory</

analysis_type></related_attribute>

</related_attribute>

<label>input</label><analysis_type>check attribute</analysis_type>

<related_attribute><atb>name</atb> <analysis_type>value</analysis_type> <content test = "=">go</content><related_attribute>

<atb>alt</atb><analysis_type>compulsory</

analysis_type></related_attribute>

</related_attribute>

a) input type=“img”alt b) input name=“go”alt

//???[@??? test “???” and not(@???) FAIL

//input[@type = “img” and not(@alt)] FAIL

//input[@name = “go” and not(@alt)] FAIL


UGL UGL

input

type

img

alt

=

a) XQuery

b) XQuery

XQuery template

2. Web Accessibility Evaluation Developers cannot be forced to use UGL

<checkpoints id="2" title="HTML elements and their attributes"><priority>1</priority><description/><evaluation_type>auto-semi</evaluation_type><techniques id="1"><type>HTML</type><description>Compulsory</description><test_case id="7">

<type>7</type><evaluation_type>auto</evaluation_type><evaluation_result>error</evaluation_result><element>

<label>IMG</label><test_e>check attribute</test_e><related_attribute>

<atb>alt</atb><test_a>compulsory</

test_a></related_attribute>

</element></test_case></techniques><techniques id="2”><test_case id="8">

<type>8</type><evaluation_type>auto</evaluation_type><evaluation_result>error</evaluation_result><element>

<label>FRAME</label><test_e>check attribute</test_e><related_attribute>

<atb>title</atb><test_a>compulsory</

test_a><content

analysis="not empty"/>Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 9

UGL An interactive web application for accessibility guidelines

- A front-end for UGL guidelines

- Creation, edition and sharing

- Working jointly with an evaluation tool

2. Web Accessibility EvaluationGuidelines Management Framework

“For each @id in textarea check there is a label where @for=@id”

1. select textarea element



2. select id attribute






3. select label element




4. select for attribute




5. define element order



Search for existing guidelines



Retrieve guidelines



Evaluate web content


user B

user A

1: user A creates, searches, shares guidelines

Definition manager

· create· search· share· update

· select guidelines· evaluate

Evaluation component

Guidelinespre-processor

browserserver

XQuery1

XQuery2

XQueryn

XQueryi

......

get XQuery2

get XQueryn

Guidelines

repository

1 2

3

5

2: guidelines are stored in a remote repository

3: guidelines are transformed into UGL4: UGL are decomposed into XQuery

4

5: user B selects guidelines and evaluates web page

http://www.foo.com


Summary for Evaluation

1. A declarative language to frame accessibility guidelines is defined

2. An interactive application allows non-expert users to manage guidelines

3. An evaluation engine works jointly with the management framework resulting in a cooperative tool for accessibility guidelines


Outline

1. Motivation





4. Contextual Web Accessibility Evaluation

5. Device-tailored accessibility

6. User-tailored accessibility

7. Conclusions


3. Web Accessibility Measurement Most broadly accepted conformance scores are WCAG

1.0 qualitative ones (0, A, AA, AAA)- Based on the assumption that if a test is violated in a level the

page fails to meet such level- We need more than accept/reject measure quantitative

metrics

Some scenarios require automatically obtained numeric scores- QA and measure of updates within Web Engineering- Accessibility Observatories- Information Retrieval- Adaptive hypermedia techniques


3.1 Web Accessibility Quantitative Metric Failure-rate is calculated for all WCAG 1.0 checkpoints

- Leads to having normalized scores- The ratio between potential and actual errors piles up close to 0- A hyperbole is applied to spread out these rates- An approach to the hyperbole

hyperbole

approach


Impact of WCAG 1.0 checkpoints is quantified The failure-rate for semi-automatic issues is estimated

3.1 Web Accessibility Quantitative MetricWAQM algorithmfor i in each checkpoint in a guideline {P,O,U,R} loop

for j in each type of checkpoint {auto,semi} loop for k in each priority{1,2,3} loop

Ai,j=calculate_failure_rate()*priority_weight(k) end for

end forAi=(Ni,auto*Ai,auto+Ni,semi*Ai,semi)/Ni

end forA=(NP*AP+NO*AO+NU*AU+NR*AR)/N

Evaluation is carried out against WCAG 1.0 Failure-rates of each checkpoints are grouped according to their

- WCAG 2.0 principle membership- reported problem type- WCAG 1.0 priorities

- All subgroups are merged weighting them with the number of checkpoints in each subgroup

- As a result A score for accessibility is obtainedAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 23

3.1 Web Accessibility Quantitative MetricValidation

Validation by experts

- Experts assessed the accessibility of 14 home pages

- EvalAccess tool was used to evaluate and WAQM was applied

- Strong positive correlation found between numeric expert assessment and WAQM r(14)=0.56, p<0.05 Testing reliability: reproducibility and consistency

- 1363 pages from 15 sites were automatically evaluated with EvalAccess and LIFT tools

- Very strong rank correlation between sites ρ(15)= 0.74 and between all pages ρ(1363)= 0.72

- No correlation was found between absolute values. A method for parameter tuning is proposed.


0

10

20

30

40

50

60

70

80

90

100EvalAccess

3.1 Web Accessibility Quantitative MetricValidation

0

50

100

150

200

250

300

350

400

10 20 30 40 50 60 70 80 90 100

Before tuning

0

50

100

150

200

250

300

350

400

450

500

10 20 30 40 50 60 70 80 90 100

LIFT

0

50

100

150

200

250

300

350

400

10 20 30 40 50 60 70 80 90 100

0

100

200

300

400

500

600

10 20 30 40 50 60 70 80 90 100

After tuning

EvalAccess

Results with parameter tuning are more similar and balanced for absolute values

while keeping strong correlation for rankings based on scores ρ(1449)=0.64, p<.000


Outline

1. Motivation


3. Web Accessibility Measurement3.1 Web Accessibility Quantitative Metric





7. Conclusions


3.1 Web Accessibility MeasurementDeploying accessibility scores in Search Engines

In a study with blind users (Ivory et al, 2004) concluded that it would be useful

WAQM was incorporated into Information Retrieval systems

1 5



A study was conducted to observe how commercial search engines behave with respect to accessibility

Google and Yahoo! search were deployed and their results ranked according to accessibility scores

Compared with Google and Yahoo! without re-ranking

12 queries from a corpus used for IR experiments were used



Results show that,- First 10 URLs provided by Yahoo and Google score pretty high- Reinforcing Pemberton’s (2003) statement on the visibility of

accessible pages- Commercial search engines do not rank results according

accessibility though- Yahoo! shows a tendency although results are not definitivekeywords Google_R vs

GoogleYahoo_R vs

Yahoo

“Vietnam war”

p>.05 τ=0.54, p<.03ρ=0.72, p<.02

“white house fellowships”

p>.05 p>.05


Summary for Measurement

1. WAQM produces numeric scores to measure accessibility

2. WAQM is valid and reliable

3. It is concluded that top 10 results produced by traditional search engines score high although not ranked according to accessibility


Outline

1. Motivation








7. Conclusions


4. Contextual Web Accessibility Even if pages meet traditional accessibility guidelines

users still find problems.

Selecting those guidelines that impact on the user is not enough- Multiple group membership is not supported by tools- Group guidelines do not capture individual needs- Guidelines contain unresolved references to user’s delivery context- Guidelines are dependent on user agents because UAAG are not

met

3 goals to capture interaction contextGoal 1. Application of multiple guideline sets

Goal 2. Overcome limitations of User Agents

Goal 3. Capture delivery contextAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 33

4. Contextual Web Accessibility Capturing the interaction context and completing

guidelines with it leads to personal web accessibility

Scenarios that would benefit from personal accessibilityEND-USERS - Personalized Information Retrieval Systems- Adaptive navigation support

DEVELOPERS- Developing Websites for Specific Audiences and Devices


The framework for context-tailored assessment requires: A vocabulary to univocally identify context features

- Gathered info is put in a CC/PP profile- CC/PP vocabulary is limited but extensible- The 5 guideline sets (WCAG, IBM, MWBP, Elderly and Learning)

have been analyzed in order to find their dependencies with respect to context

A vocabulary is created with those features that refer to context in accessibility guidelines- Same concepts from other vocabularies have been borrowed

4. Contextual Web Accessibility Framework for personal accessibility


Goal 2. With respect to ATs two types of dependencies are identified:- Negative dependencies: older versions may suffer accessibility problems even if

guidelines are met false negatives- Positive dependencies: new features of ATs make some accessibility barriers

obsolete false positives

4. Contextual Web Accessibility Framework for personal accessibility – creating a vocabulary for context profiles

feature Jaws versio

n

dependence

type

WCAG MWBP IBM elderly

learning

frames navigation

3.71 negative 1.1, 12.1, 12.2

NO_FRAMES 9 N/A 6.1, 6.3, 8.2

control auto-refreshing

4.5 positive 7.4, 10.1

AUTO_REFRESH 13 N/A N/A


Goal 3. Those references that guidelines make to the delivery context are captured


Best practice

Description concept type word

SCROLLING check that pictures are not wider that screen width

available screen size

dimension

prf:ScreenSize

OBJECTS OR SCRIPTS

check support for scripts, flash or applets

supported formats

resource access:FormatSupport


Goal 1: Multiple guideline sets repository of UGL guidelines


UGL reposit

ory

Goal 2: Overcome user agent limitations A detector of installed ATs

Assistive Technologi

es Detector


Goal 3: Capture the Delivery Context Device information retrieval from heterogeneous

repositories- UAProf profiles: extended CC/PP profiles describing device

features- WURFL profile: XML file containing device descriptions- Device Atlas: device description files


Device Informat

ion Retrieve

r

Jena

WURLF

UAProf

Device

Atlas

API

JSON


Extracted information is put in a CC/PP profile using the defined vocabulary


Device Information Retriever

WURLFUAProf

Device

Atlas

Assistive Technologies detector

<software features/><hardware features/><assistive technologies/>

CC/PP Profile


Automatically obtained CC/PP profile for personal accessibility


<rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"xmlns:ccpp="http://www.w3.org/2000/07/04-ccpp#"xmlns:access="http://sipt07.si.ehu.es/profiles/2008/access-schema#"><rdf:Description rdf:about="http://sipt07.si.ehu.es/profiles/2008/user_0017"> <ccpp:component rdf:resource="http://www.w3.org/2000/07/04-ccpp#HardwarePlatform"/> <ccpp:component rdf:resource="http://www.w3.org/2000/07/04-ccpp#SoftwarePlatform"/> <ccpp:component rdf:resource="http://sipt07.si.ehu.es/profiles/2008/access-schema#AT"/></rdf:Description><rdf:Description rdf:about="http://www.w3.org/2000/07/04-ccpp#HardwarePlatform"> <access:CpuName>AMD Athlon(tm) XP 2400+</access:CpuName> <access:CpuConstructor>AuthenticAMD</access:CpuConstructor> <access:ramSize>1035172 kB</access:ramSize> <access:display>1024 x 768 pixels</access:display> <access:keyboard>AT Translated Set 2 keyboard</access:keyboard> <access:ColourCapable>Yes</access:ColourCapable> <access:ImageCapable>Yes</access:ImageCapable> <access:SoundOutputCapable>Yes</access:SoundOutputCapable ></rdf:Description><rdf:Description rdf:about="http://www.w3.org/2000/07/04-ccpp#SoftwarePlatform"> <access:OSName>Linux</access:OSName> <access:OSVendor>Unknown</access:OSVendor> <access:OSVersion>2.6.9-1.667</access:OSVersion> <access:user>root</access:user> <access:JavaVersion>1.4.2_10</access:JavaVersion> <access:JavaVendor>Sun Microsystems Inc.</access:JavaVendor> <access:JavaVendorURL>http://java.sun.com/</access:JavaVendorURL></rdf:Description><rdf:Description rdf:about="http://sipt07.si.ehu.es/profiles/2008/access-schema#AT"> <access:ATName>Brltty</access:ATName> <access:ATVendor>The Brltty Team</access:ATVendor> <access:ATVersion>3.6.1</access:ATVersion> <access:ATType>Output</access:ATType>

<access:ATIOtype>Braille</access:ATIOtype></rdf:Description><rdf:Description rdf:about="http://sipt07.si.ehu.es/profiles/2008/access-schema#AT"> <access:ATName>K magnifier</access:ATName> <access:ATVendor>Kde Access Team</access:ATVendor> <access:ATVersion>1.0.0</access:ATVersion> <access:ATType>Output</access:ATType> <access:ATDescription>KDE Accessibility Magnifier</access:ATDescription> <access:ATIOtype>Magnifier</access:ATIOtype></rdf:Description>

access namespacehardware

features

softwarefeatures

assistivetechnologies


The Guidelines Manager based on the data of the CC/PP profile



WURLFUAProf

Device

Atlas


<software features/><hardware features/><assistive technologies/>CC/PP

Profile

Goal 1. Only those guidelines that affect to the user are downloaded

Goal 2. Guidelines with positive dependencies are not evaluated

Goal 2. Guidelines with negative dependencies will produce a failure

Goal 3. Guidelines are completed with delivery context data

UGL reposito

ry

Guidelines Manager


Example: IMAGE_MAPS best practice UGL is extended with semantic information

4. Contextual Web Accessibility Guidelines & Profiles

<access:pntSupport>true</access:pntSupport>

<test_case id="8"><evaluation_type>auto</evaluation_type><evaluation_result>error</evaluation_result><profile_feature type="access:pntSupport"/><value> </value><element>

<label>OBJECT</label><test_elem>check attribute</test_elem><related_attribute>

<atb>ismap</atb></related_attribute>

</element></test_case>

let $tmp:=web_doc.xml//OBJECT[@ismap] return if(not( ))thenfor $i in $tmp return<error>{$i/@line, $i/name()}</error>

CC/PP excerpt

UGL excerpt

XQuery excerpt

1. Matching

2. Fill in slotstrue

true




WURLFUAProf

Device

Atlas


<software features/><hardware features/><assistive technologies/>CC/PP

Profile

UGL reposito

ry

Guidelines Manager

<html><head><title>Test file<title><body>foo

(X)HTML

XQuery1

XQueryi

XQueryn

Context-tailored report

A set of context-tailored evaluation tests are produced

As a result, evaluation report is tailored to context


WAQM is strongly tied to WCAG guidelines A more flexible aggregation method that can be adapted to

different interaction contexts is thus applied

4. Contextual Web Accessibility Applying metrics

Traditional aggregation:

€

E=W1E1 +.. +WiEi +.. +WnEnwhere W: weights and E: evaluation results

Logic Scoring Preferences:

€

E= W1E1ρ( d)

+.. +WiEiρ( d)

+.. +WnEnρ(d) ⎛

⎝ ⎜

⎞ ⎠ ⎟1ρ( d)

where ρ(d) are values selected upon the required logical relationship between evaluation results

Successfully applied by Olsina & Rossi (2002) in web application Quality Assurance scenarios


Summary for Contextual Evaluation

1. An assessment framework that considers interaction context

2. How assistive technologies provide access to content and device features are of utmost importance

3. A metric that adapts to different contextual settings is defined


Outline

1. Motivation








7. Conclusions


5. Device-Tailored Web Accessibility - developers

Mobile Web Best Practices with different devicesTool effectiveness 10 pages were evaluated for different devices

- D1<D2<D3- Device-tailored vs traditional evaluation

Device-tailored evaluation statistically differs Following Brajnik’s (2004) method for tool

effectiveness- False positives of warnings are removed increase in tool

completeness- More false negatives of failures are found increase tool

correctness- Mobile Web Guidelines are developed in a low specifity levelAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 50

5. Device-Tailored Web Accessibility - developers

Device/paradigm behaviour Logic Scoring Preferences was applied

- 5 metrics: Navigation, Layout, Page Definition, Input and Overall- 102 web pages mobile vs desktop- D1<D2

Higher scores are obtained for pages to be deployed in mobile devices

Better featured devices score higher


5. Device-Tailored Web Accessibility - end users

Context: able-bodied users accessing the web with mobile devices

Access device: a PDA Guidelines: mobileOK tests for mobile web

conformance 20 participants Task: search by navigating Usability measures

- Effectiveness: completed task rate- Efficiency: task completion time- Satisfaction: Lewis’ after scenario questionnaire



Assessment metrics: device-tailored vs non-tailored Correlation matrix: *:p<.05, **:p<.03, ***:p<.00

metric paradigm effectiveness

efficiency

satisfaction

overall no context 0.45 -0.81*** 0.74**

context 5 -0.88*** 0.67*

navigation

no context 0.42 -0.70* 0.73**

context 0.55 -0.82*** 0.82***

input no context 0.47 -0.94*** 0.49

context 0.48 -0.94*** 0.50



Discussion Automatic conformance to guidelines entails higher

usability levels even for non-contextual assessment

Device-tailored assessment correlates stronger than non-tailored assessment

Against the common belief that tool conformance does entail usability


Summary for Device-Tailored Evaluation

1. Device features are considered when evaluating mobile web guidelines

2. Tool effectiveness increases

3. User test shows that device-tailored approach is more faithful with the actual user experience


Outline

1. Motivation








7. Conclusions


6. User-Tailored Web Accessibility Assessment

Context: blind users accessing the web with screen reader

Technique: deploying assessment results as link annotations.

Hypothesis: user orientation will increasescore:

21

score: 72

score:49



Context: blind users accessing the web with screen reader

Access device: desktop computer User agent: Jaws screen reader Guidelines: web guidelines for the blind

- Usability Guidelines for the Blind [Leporini & Paternò, 08]

- Subset of WCAG 1.0 for blind users Tasks:

1. Browsing by navigating

2. Searching by navigating



Task 1. browsing by navigating Goal: observe users with no/vague target in mind Results

- Page without annotations most users proceeded sequentially

- Page with no one followed the expected most accessible path

- However, when aggregating accessibility scores of visited pages, 7 points over the median are obtained

- It can be interpreted as if the users browsed within the subset of more accessible pages according to random/preference criteria



Task 2. searching by navigating Goal: observe users with a specific target in mind Results

- Page without annotations few users proceeded sequentially- Page with annotations few users proceeded sequentially but

only one followed the expected most accessible path

- Again, when aggregating accessibility scores of visited pages 6 points over the median are obtained

- This, can be interpreted as if the users browsed within the subset of more accessible pages according to random/preference criteria



Discussion After-use questionnaire: scores are useful to a certain

extent Users find accessibility annotations useful in those

scenarios where the topic of the linked pages is similar Informal comments: annotation technique prevails

over scores In the searching scenario users do search within the

subset of most accessible links In the browsing scenario users change paradigm

- From sequential browsing to random in the subset of most accessible links

- Subjective scores are more balanced than in the searching scenarioAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 63


Implications for Design Annotation technique would better fit in an scenario when: - users browse casually - and topics of linked pages are similar

E.g., on the leaf nodes of a web directory


Summary for User-Tailored Evaluation

1. Particular needs of screen reader users are considered in the assessment process

2. A novel technique: hyperlinks are annotated with accessibility scores

3. Users do not browse sequentially anymore


Outline

1. Motivation








7. Conclusions


7. Conclusions

Web accessibility assessment from a broad perspective to a more specific one where context is taken into account

A declarative language to frame most of existing web guidelines

A framework for guidelines managing- Interoperable with evaluation tool- Cooperative online tool for researchers and practitioners

A quantitative metric (WAQM) that overcomes the limitations of previous ones- Valid according to expert assessment- Reliable in all scenarios

WAQM has been applied in a real scenario- Leads to empirically corroborate search engine visibility of accessible

pagesAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 67

7. Conclusions A framework for contextual accessibility assessment

- Analysis of those contextual factors that impact on content guidelines

- The components that take part are identified Device-tailored assessment

- Tool effectiveness is increased when delivery context is considered- Study on device-paradigm: better featured devices provide a

better experience- Device-tailored approach has a stronger correlation with usability

User-tailored assessment- A novel annotation technique- Users change paradigm- Fits better in a scenario where links are similar wrt topic and users

browse casuallyAutomatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 68

Future Works Extend evaluation to the DOM

A Quality Model for Web Accessibility Metrics

Conduct large-scale studies on Search Engines behaviour

A tool for automatic link annotation


Publications – Journals Vigo, M., Aizpurua, A., Arrue, M., and Abascal, J. (2009).

Automatic Device-Tailored Evaluation of Mobile Web Guidelines. New Review of Hypermedia and Multimedia 15(3), 1-22. Tailor & Francis

Vigo, M., Brajnik, G., Arrue, M., and Abascal, J. (2009). Tool Independence for the Web Accessibility Quantitative Metric. Disability and Rehabilitation: Assistive Technology 4(4), 248-263. Tailor & Francis

Vigo, M., Arrue, M., and Abascal, J. (2009). Enriching Information Retrieval Results with Web Accessibility Measurement. Journal of Web Engineering 8(1), 3-24. Rinton Press

Arrue, M., Vigo, M., and Abascal, J. (2008). Web Accessibility Awareness in Search Engine Results. Universal Access in the Information Society 7(1-2), 103-116. Springer


Publications – Conferences Vigo, M., Leporini, B., and Paternò, F. (2009). Enriching Web Information Scent for Blind

Users. ACM SIGACCESS Conference on Computers and Accessibility, ASSETS’09, 123-130. ACM Press.

Aizpurua, A., Arrue, M., Vigo, M., and Abascal, J. (2009). Transition of Accessibility Evaluation Tools to New Standards. International Cross-Disciplinary Conference on Web Accessibility, W4A’09, 36-44. ACM Press.

Vigo, M., Aizpurua, A., Arrue, M., and Abascal, J. (2008). Evaluating Web Accessibility for Specific Mobile Devices. International Cross-Disciplinary Conference on Web Accessibility, W4A’08, 65-72. ACM Press.

Arrue M., Vigo M., and Abascal J. (2008). Including Heterogeneous Web Accessibility Guidelines in the Development Process. Engineering Interactive Systems, EIS’07. LNCS 4940, 620-637. Springer

Vigo, M., Kobsa, A., Arrue, M., and Abascal, J. (2007). User-Tailored Web Accessibility Evaluations. 18th ACM Conference on Hypertext and Hypermedia, Hypertext’07, 95-104. ACM Press

Arrue M., and Vigo M. (2007). Considering Web Accessibility in Information Retrieval Systems. Web Engineering: International Conference on Web Engineering 2007, ICWE’07. LNCS 4607, 370-384. Springer

Vigo, M., Arrue, M., Brajnik, G., Lomuscio, R., and Abascal, J. (2007). Quantitative Metrics for Measuring Web Accessibility. International Cross-Disciplinary Conference on Web Accessibility, W4A’07, 99-107. ACM Press.Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement and Adaptation Perspective 71

Automatic Assessment of Contextual Web Accessibility from an Evaluation, Measurement andAdaptation Perspective

Candidate: Markel Vigo EchebarriaAdvisor: Julio Abascal González

Donostia, November 23rd 2009

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Candidate: Markel Vigo Echebarria Advisor: Julio Abascal González Donostia, November 23rd 2009.

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