Research colloquium at Tübingen University held on 24 September 2020, introducing methods and research facilitated by the Web.

1. 1Stefan Dietze
Backup
Human-in-the-Loop: the Web as Foundation for interdisciplinary
Data Science Methods and Research Questions
Stefan Dietze
GESIS - Leibniz Institute for the Social Sciences,
Heinrich-Heine-University Düsseldorf,
L3S Research Center

2. 2Stefan Dietze
Interdisciplinary research facilitated by the Web
 Rapidly growing interdisciplinary research exploiting the Web for investigating online
behavior, e.g. with respect to knowledge construction and exchange, network effects,
or virality of disinformation (e.g. Vousoughi et al. 2018)
 Focused on gaining insights (e.g. social sciences, psychology) by understanding Web
data with the help of computational methods
Understanding & interpreting user behaviour & interactions
 Behaviour and interactions with online platforms (e.g. Web
search engines and social media platforms) & online
content (eg Tweets)
 Signals: click-through data, queries, shares, likes,
behavioral traces (mouse movements, navigation, eye
tracking etc)
Machine & representation learning, information retrieval, NLP and knowledge-based approaches for:
Understanding & intepreting (user-generated) Web content
 Content: web pages, social media posts, comments etc
 Extraction, verification, disambiguation of topics, entities,
stances, opinions, sentiments (semantics)
 Understanding language complexity, structure or modality
of online resources

3. 3Stefan Dietze
Overview
 Understanding competence, information needs,
knowledge gain of users from behavioral traces
 Scenarios: Web search, microtask crowdsourcing
 Extraction & verification of factual knowledge & claims
 Stance detection of websites
 Understanding discourse/opinions/trends (Twitter)
Part IIPart I
Understanding & interpreting user behaviour & interactions
 Behaviour and interactions with online platforms (e.g. Web
search engines and social media platforms) & online
content (eg Tweets)
 Signals: click-through data, queries, shares, likes,
behavioral traces (mouse movements, navigation, eye
tracking etc)
Understanding & intepreting (user-generated) Web content
 Content: web pages, social media posts, comments etc
 Extraction, verification, disambiguation of topics, entities,
stances, opinions, sentiments (semantics)
 Understanding language complexity, structure or modality
of online resources

4. 4Stefan Dietze
Extraction of "long-tail" factual knowledge on the web ?
<"Tim Berners-Lee" s:founderOf "Solid">
 How can entity-centric factual knowledge be extracted from
websites?
 Application of NLP/information extraction methods on 60 billion
Web pages (Google index)?
 Widespread adoption of embedded web markup
(Microdata/RDFa, schema.org): about 40% of all Common Crawl
web pages (3.2 billion Web pages) contain markup (about 44
billion "facts")
 Challenges
o Errors. Annotation errors and factual errors [Meusel et al,
ESWC2015]
o Ambiguity and co-references. e.g. 18,000 markup instances
of "iPhone 6" in Common Crawl 2016 & ambiguous literals
(e.g. "Apple")
o Redundancies & conflicts. large proportion of equivalent or
directly conflicting statements

5. 5Stefan Dietze
KnowMore: data fusion on Web Markup
 0. Noise: data cleansing (URIs, deduplication etc)
 1.a) Scale: blocking with BM25 entity retrieval on Lucene index of markup data
 1.b) Relevance: supervised resolution of coreferences
 2.) Quality & Redundancy: Data Fusion with supervised classifier for all facts (SVM, knn, CNN, RF, LR, NB), uses various feature sets
(authority, relevance etc) of source (e.g. PageRank), entity description or facts
1. Blocking &
coreference resolution
2. Fusion / fact selection
(supervised)
Web page
markup
Web crawl
(Common Crawl,
44 bn facts)
Yu, R., [..], Dietze, S., KnowMore-Knowledge Base
Augmentation with Structured Web Markup, Semantic Web
Journal 2019 (SWJ2019)
Tempelmeier, N., Demidova, S., Dietze, S., Inferring Missing
Categorical Information in Noisy and Sparse Web Markup,
The Web Conf. 2018 (WWW2018)
New Query Entities
BBC Audio, type:(Organization)
Chapman & Hall, type:(Publisher)
Put Out More Flags, type:(Book)
Entity Description
author Evelyn Waugh
priorWork Put Out More Flags
ISBN 978031874803074
copyrightHolder Evelyn Waugh
releaseDate 1945
… …
Query Entity
Brideshead Revisited, type:(Book)
Candidate Facts
node1 publisher Chapman & Hall
node1 releaseDate 1945
node1 publishDate 1961
node2 country UK
node2 publisher Black Bay Books
node3 country US
node3 copyrightHolder Evelyn Waugh
… …. ….
About 5000 facts for "Brideshead Revisited
(125.000 facts for "iPhone6")
20 correct & non-redundant facts for "Brideshead Rev.

6. 6Stefan Dietze
KnowMore: data fusion on Web Markup
 0. Noise: data cleansing (URIs, deduplication etc)
 1.a) Scale: blocking with BM25 entity retrieval on Lucene index of markup data
 1.b) Relevance: supervised resolution of coreferences
 2.) Quality & Redundancy: Data Fusion with supervised classifier for all facts (SVM, knn, CNN, RF, LR, NB), uses various feature sets
(authority, relevance etc) of source (e.g. PageRank), entity description or facts
1. Blocking &
coreference resolution
2. Fusion / fact selection
(supervised)
Web page
markup
Web crawl
(Common Crawl,
44 bn facts)
Yu, R., [..], Dietze, S., KnowMore-Knowledge Base
Augmentation with Structured Web Markup, Semantic Web
Journal 2019 (SWJ2019)
Tempelmeier, N., Demidova, S., Dietze, S., Inferring Missing
Categorical Information in Noisy and Sparse Web Markup,
The Web Conf. 2018 (WWW2018)
New Query Entities
BBC Audio, type:(Organization)
Chapman & Hall, type:(Publisher)
Put Out More Flags, type:(Book)
Entity Description
author Evelyn Waugh
priorWork Put Out More Flags
ISBN 978031874803074
copyrightHolder Evelyn Waugh
releaseDate 1945
… …
Query Entity
Brideshead Revisited, type:(Book)
Candidate Facts
node1 publisher Chapman & Hall
node1 releaseDate 1945
node1 publishDate 1961
node2 country UK
node2 publisher Black Bay Books
node3 country US
node3 copyrightHolder Evelyn Waugh
… …. ….
About 5000 facts for "Brideshead Revisited
(125.000 facts for "iPhone6")
20 correct & non-redundant facts for "Brideshead Rev.
Data fusion performance
 Experiments for books, films, products
 Baselines: BM25, CBFS [ESWC2015], PreRecCorr [Pochampally et.
al., ACM SIGMOD 2014], vary widely between types
Enriching knowledge graphs / finding new facts?
 On average 60% - 70% of all facts are new (compared to
knowledge graphs like WikiData, Freebase, Wikipedia/DBpedia)
 Experiments for learning categorical characteristics (e.g. film
genres or product categories) [WWW2018].

7. 7Stefan Dietze
Understanding discourse & opinions on Twitter
http://dbpedia.org/resource/Tim_Berners-Lee
wna:positive-emotion
onyx:hasEmotionIntensity "0.75
onyx:hasEmotionIntensity "0.0
 Heterogeneity: multimodal, multilingual,
informal, "noisy" language
 Context dependency: interpretation of short
tweets requires consideration of context (e.g.
time, linked content), "Dusseldorf" => city or
football team
 Representativity & bias: demographic
distributions in Twitter archives not known
 Dynamics & scale: e.g. 8000 tweets per second,
plus interactions (retweets etc) & context (e.g.
25% of all tweets contain URLs)
 Evolution & temporal aspects: Evolution of
interactions over time important for most
research questions
http://dbpedia.org/resource/Solid
wna:negative-emotion
P. Fafalios, V. Iosifidis, E. Ntoutsi, and S. Dietze,
TweetsKB: A Public and Large-Scale RDF Corpus of
Annotated Tweets, ESWC'18.

8. 8Stefan Dietze
TweetsKB: a knowledge base of Web mined societal discourse
P. Fafalios, V. Iosifidis, E. Ntoutsi, and S. Dietze,
TweetsKB: A Public and Large-Scale RDF Corpus of
Annotated Tweets, ESWC'18.
https://data.gesis.org/tweetskb/
 Collection & archiving of 10 billion tweets over 7 years
(permanent crawl of Twitter 1% API since 2013)
 Information extraction using NLP methods to extract
entities and sentiments (distributed batch processing
with Hadoop Map/Reduce)
o Entity linking with Wikipedia/DBpedia (Yahoo's FEL
[Blanco et al. 2015])
("president"/"potus"/"trump" => dbp:DonaldTrump), to
disambiguate tweets and link to background knowledge
(e.g. US politicians? Republicans?), high precision (.85),
poor recall (. 39)
o Sentiment analysis with SentiStrength [Thelwall et al.,
2017], F1 approx. . 80
o Extraction of metadata and lifting into established
formats and schemas (SIOC, schema.org), publication
using W3C standards (RDF/SPARQL)

9. 10Stefan Dietze
TweetsCOV19: a knowledge graph of societal discourse on COVID19
Dimitrov, D., Baran, E., Fafalios, P., Yu, R., Zhu, X., Zloch, M., Dietze,
S., TweetsCOV19 -- A Knowledge Base of Semantically Annotated
Tweets about the COVID-19 Pandemic, CIKM2020.
https://data.gesis.org/tweetscov19/
 COVID19 discourse as foundation for
interdisciplinary research on solidarity behaviour
& societal changes during the pandemic
 8.1 million tweets since October 2019
(continuously updated), extracted using COVID-19
specific seed list & TweetsKB pipeline
 Used as corpus for CIKM2020 AnalytiCup & by
interdisciplinary partners, e.g. with the Federal
Statistical Office, Media & Communication
Studies @ Heinrich-Heine-University, University of
Hildesheim, etc.

10. 11Stefan Dietze
Understanding claims & stances on the Web

11. 12Stefan Dietze
Stance,
Trustworthiness of the
claim?
Stance,
Trustworthiness of the claim?
Understanding claims & stances on the Web

12. 14Stefan Dietze
A hierarchical stance detection classifier
Motivation
 Problem: identifying stance of web documents (web pages,
tweets) on a specific claim
(class distribution highly unbalanced)
 Applications: stance of documents (especially disagreement)
important (a) as signal correctness of statement and (b) for the
classification of sources (Twitter users, PLDs)
Roy, A. Ekbal, S. Dietze, P. Fafalios, Exploiting stance hierarchies for cost-
sensitive stance detection of Web documents, preprint/Arxiv.
A. Tchechmedjiev, P. Fafalios, K. Boland, S. Dietze, B. Zapilko, K. Todorov,
ClaimsKG - A Live Knowledge Graph of fact-checked Claims, ISWC2019

13. 15Stefan Dietze
Motivation
 Problem: identifying stance of web documents (web pages,
tweets) on a specific claim
(class distribution highly unbalanced)
 Applications: stance of documents (especially disagreement)
important (a) as signal correctness of statement and (b) for the
classification of sources (Twitter users, PLDs)
Approach
 Cascading binary classifiers to address problems at each step
(e.g. cost of misclassification)
 Features, e.g. text similarity (Word2Vec etc), sentiments, LIWC
 Best models per step: 1) SVM with class-wise penalty, 2) CNN, 3)
SVM with class-wise penalty
 Experiments with Fake News Challenge Benchmark Dataset &
baselines
Results
 Minor overall performance improvement
 27% improvement for disagree class
A hierarchical stance detection classifier Roy, A. Ekbal, S. Dietze, P. Fafalios, Exploiting stance hierarchies for cost-
sensitive stance detection of Web documents, preprint/Arxiv.
A. Tchechmedjiev, P. Fafalios, K. Boland, S. Dietze, B. Zapilko, K. Todorov,
ClaimsKG - A Live Knowledge Graph of fact-checked Claims, ISWC2019

14. 16Stefan Dietze
 Extraction & verification of factual knowledge & claims
 Stance detection of websites
 Extraction of opinions/trends (Twitter)
Overview
Understanding & intepreting (user-generated) Web content
 Content: web pages, social media posts, etc
 Extraction, verification, disambiguation of topics, entities,
stances, opinions, sentiments (semantics)
 Understanding language complexity, structure or modality
of online resources
 Understanding competence, information needs,
knowledge gain of users from behavioral traces
 Scenarios: Web search, microtask crowdsourcing
Part IIPart I
Understanding & interpreting user behaviour & interactions
 Behaviour and interactions with online platforms (e.g. Web
search engines and social media platforms) & online
content (eg Tweets)
 Signals: click-through data, queries, shares, likes,
behavioral traces (mouse movements, navigation, eye
tracking etc)

15. 17Stefan Dietze
Competence & knowledge acquisition of web users
Prediction from in-session behavior?
 Research questions: Is it possible to predict the
competence and knowledge acquisition of users on
the basis of user interactions such as browsing,
scrolling, or behavioral traces (mouse movements,
keystrokes, eye tracking)?
 Approach: Studies and machine learning models in
two scenarios: (a) Web Search and (b) Microtask
Crowdsourcing like Amazon Mechanical Turk
 Applications: e.g. for the classification of web users,
improvement of search results or the adaptation in
learning and assessment environments
Gadiraju, U., Kawase, R., Dietze, S, Demartini, G., Understanding Malicious Behavior in
Crowdsourcing Platforms: The Case of Online Surveys, ACM CHI2015.
Gadiraju, U., Demartini, G., Kawase, R., Dietze, S., Crowd Anatomy Beyond the Good
and Bad: Behavioral Traces for Crowd Worker Modeling and Pre-selection, Computer
Supported Cooperative Work 28(5): 815-841 (2019)

16. 18Stefan Dietze
Acquisition of knowledge during web search?
Challenges & results
 Identifying coherent search missions?
 Identification of "learning" during search: identification of
"informational sessions" (as opposed to "transactional" or
"navigational" search [Broder, 2002])
o Classification with approx. F1 score 75% based on user
interactions
 How competent is the user? -
Predicting and understanding the competence / knowledge level
of users based on "in-session" behaviour
 How well does a user achieve his/her learning objective or
information need? - Predicting the knowledge state/gain during
a session
o Correlation of user behaviour (queries, browsing, mouse
movements etc) & knowledge state/gain [CHIIR18]
o Prediction of knowledge state/gain using supervised ML
methods [SIGIR18].

17. 19Stefan Dietze
Knowledge level & growth vs user behaviour in web search
Data & experimental setup
 Crowdsourcing of behavioral data in search sessions
 10 topics/information needs (e.g. "altitude sickness", "tornados") plus
pre- and post-tests to determine knowledge state and knowledge gain
(KS, KG)
 Approx. 1000 crowd workers; 100 sessions per topic
 Monitoring of user behavior along 76 features in 5 categories: session,
query, SERP - search engine result page, browsing, mouse traces
Results
 70% of users show knowledge gain (KG)
 Negative correlation between KG & topic popularity (avg. accuracy of
workers in knowledge tests) (R= -.87)
 Time spent actively on websites explains 7% of knowledge gain
 Query complexity explains 25% of knowledge gain
 Search behavior correlates more strongly with search topic than with
KG/KS
Gadiraju, U., Yu, R., Dietze, S., Holtz, P.,. Analyzing
Knowledge Gain of Users in Informational Search
Sessions on the Web. ACM CHIIR 2018.

18. 20Stefan Dietze
ML models to predict KG/KS during Web search
 Categorisation of the sessions along knowledge state (KS) & knowledge gain (KG)
in {low, moderate, high} with (low < (mean ± 0.5 SD) < high)
 Supervised multiclass classification (Naive Bayes, Logistic Regression, SVM, Random Forest, Multilayer
Perceptron)
 KG prediction performance
(after 10-fold cross-validation)
 Feature impact (KG prediction)
Yu, R., Gadiraju, U., Holtz, P., Rokicki, M., Kemkes, P., Dietze, S.,
Analyzing Knowledge Gain of Users in Informational Search
Sessions on the Web. ACM SIGIR 2018.

19. 21Stefan Dietze
ML models to predict KG/KS during the search
 Categorisation of the sessions along knowledge state (KS) & knowledge gain (KG)
in {low, moderate, high} with (low < (mean ± 0.5 SD) < high)
 Supervised multiclass classification (Naive Bayes, Logistic Regression, SVM, Random Forest, Multilayer
Perceptron)
 KG predicition performance
(after 10-fold cross-validation)
 Feature impact (KG prediction)
Yu, R., Gadiraju, U., Holtz, P., Rokicki, M., Kemkes, P., Dietze, S.,
Analyzing Knowledge Gain of Users in Informational Search
Sessions on the Web. ACM SIGIR 2018.
Ongoing work
 Lab studies necessary for more reliable data
(controlled environment, longer sessions)
[completed]
 Additional behavioral features (eye tracking)
[CHIIR2020, CHI2020]
 Ressource features (e.g. complexity,
analytic/emotional language, multimodality etc) as
additional signals [IR Journal, under review]
 Improve ranking/retrieval in web search or in digital
archives
(SALIENT Project, Leibniz Cooperative Excellence;
GESIS Data Search platforms)

20. 22Stefan Dietze
Other features to predict competence?
Expertise & the "Dunning-Kruger Effect
 Incompetence in a particular task reduces the ability to
recognise one's own incompetence in the task
(David Dunning. 2011 The Dunning-Kruger Effect: On Being Ignorant of One's Own Ignorance.
Advances in experimental social psychology 44 (2011), 247.)
Research questions
 Self-assessment as an additional feature to predict
competence?
 Application in microtask crowdsourcing for the classification
of "workers" or in online learning for the classification of
learners
Some results
 Self-assessment as a reliable feature for predicting
competence/future performance;
 More reliable than prior performance in the task alone
 The tendency to overestimate one's own competence grows
with increasing task difficulty Performance ("accuracy") of users classified as "competent" according to (1) prior
performance and (2) performance plus self-assessment
Gadiraju, U., Fetahu, B., Kawase, R., Siehndel, P., Dietze, S.,
Using Worker Self-Assessments for Competence-based Pre-
Selection in Crowdsourcing Microtasks. In: ACM Transactions
on Computer-Human Interaction (ACM TOCHI), Vol. 24,
Issue 4, August 2017.

21. 23Stefan Dietze
Knowledge Technologies for the Social Sciences (WTS)
https://www.gesis.org/en/institute/departments/knowledge-technologies-for-
the-social-sciences/
Data & Knowledge Engineering @ HHU
https://www.cs.hhu.de/en/research-groups/data-knowledge-engineering.html
@stefandietze
http://stefandietze.net
Acknowledgements
• Erdal Baran (GESIS, Germany)
• Katarina Boland (GESIS, Germany)
• Stefan Conrad (HHU, Germany)
• Gianluca Demartini (Brisbane Uni, Australia)
• Elena Demidova (L3S, Germany)
• Dimitar Dimitrov (GESIS, Germany)
• Ujwal Gadiraju (Delft University, NL)
• Asif Ekbal (IIT Patna, India)
• Pavlos Fafalios (FORTH ICS, Greece)
• Peter Holtz (IWM, Tübingen)
• Ricardo Kawase (Mobile.de, Germany)
• Vasileios Iosifidis (L3S, Germany)
• Eirini Ntoutsi (LUH, Germany)
• Vasilis Iosifidis (L3S, Germany)
• Markus Rokicki (L3S, Germany)
• Arjun Roy (IIT Patna, India)
• Patrick Siehndel (L3S, Germany)
• Nicolas Tempelmeier (L3S, Germany)
• Konstantin Todorov (LIRMM, France)
• Ran Yu (GESIS, Germany)
• Benjamin Zapilko (GESIS, Germany)
• Matthäus Zloch (GESIS, Germany)
• Xiaofei Zhu (Chongqing University, China)