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If you are interested in a fully-funded 4-year PhD position or a 2-year Postdoc position in NLP and/or information retrieval, please get in touch with Claudia Hauff ( The positions are open as of April 2019.

Recent & Upcoming Activities

  • May 2019: Guanliang Chen (MOOC Analytics: Learner Modeling and Content Generation) and Dan Davis (Large-Scale Learning Analytics: Modeling Learner Behavior & Improving Learning Outcomes in Massive Open Online Courses) defend their PhD theses.
  • February 2019: Dimitrios Bountouridis is at FAT* 2019, presenting our work on SIREN, a prototype to understand the effects of recommender systems in online news environments (check the blog post on the paper).

  • December 2018: Our Springer Information Retrieval journal article On the Impact of Group Size on Collaborative Search Effectiveness, led by Felipe Moraes and Kilian Grashoff is on the road to being published. Check the preprint here.

  • November 2018: Gustavo Penha and Arthur Barbosa Câmara join the Lambda team as PhD students, working on information retrieval.

Why the Name?

It is tradition in our research group to form teams around Greek letters, usually a letter that is associated with a major topic of the team. And thus we picked Lambda to highlight Learning. Sigma (which would have been another obvious choice due to Search) was already taken.

Research Focus

Lambda-Lab brings together research expertise in data science and information retrieval (IR). Core IR topics (such as collaborative search, conversational search and data-hungry ranking models) are investigated as well as applications of data science and IR to application domains, most prominently the domain of Massive Open Online Learning. TU Delft is one of the largest MOOC providers in Europe and as such offers a unique research environment to investigate and explore human learning in a computational and large-scale manner. With more than 80 TU Delft MOOCs running on the edX platform and more than 2 million registered learners (end of 2018), we have a rare opportunity to empirically explore and evaluate learning interventions (which are often designed around learners' searching for information).

Researchers Involved

Several researchers of the WIS group currently contribute to this research line:

  • Claudia Hauff is an Associate Professor at WIS and the lab leader of Lambda-Lab. She is the daily supervisor of all MSc and PhD projects within this research line. Contact her via with any questions about Lambda-Lab.
  • Felipe Moraes' PhD is financed by NWO (TOP2 grant) and works on collaborative search questions in the setting of MOOCs.
  • Arthur Câmara's PhD is financed by NWO (VIDI grant) and focuses on search for learning, with a special focus on neural IR models.
  • Gustavo Penha's PhD is financed by NWO (VIDI grant) and zooms in on the problem of conversational search in the context of MOOCs.
  • Dimitrios Bountouridis is a Postdoc financed by NWA working on fairness and transparancy in the context of various IR, RecSys and NLP problems.

Past members include:

  • Dan Davis (PhD student, 2015-2019, supported by CEL) researched the impact of the online learning environment on learners and learning. His PhD thesis is available here.
  • Guanliang Chen (PhD student, 2015-2019, supported by TU Delft's Extension School) explored data sources beyond the MOOC platforms themselves to explore learner modeling and content generation. His PhD thesis can be found here.
  • Yue Zhao (PhD student, 2014-2019, supported by a CSC grant) employed data analytics to make sense of MOOC learners' behaviour. His PhD thesis can be found here.
  • Mónica Marrero (research engineer, 2017-2018).

Lambda-Lab is also the host of a number of Master students:

  • Daan Rennings innvestigates the axiomatic approach to information retrieval (IR), specifically for neural IR models.
  • Nirmal Roy explores word embeddings and how to use them to improve adhoc retrieval.
  • Kun Jiang's focus is on question answering and how to improve the first step of the QA pipeline (i.e. the retrieval system).
  • Alex Balan investigates conversational search problems.
  • Francisco Morales also investigates the use of IR technologies for NLP problems.
  • Wanning Yang investigates the use of IR technologies for NLP problems.
  • Kilian Grashoff explored the impact of group size on collaborative search. He defended his thesis in January 2019, and contributed to a DESIRES 2018 paper and an Information Retrieval Journal article (2019).
  • Sindu Sindunuraga Rikarno Putra investigated to what extent search is a viable alternative to learning from MOOC videos. He defended his thesis in August 2018. Sindu's thesis work contributed to a SIGIR 2018 demo, a DESIRES 2018paper and a full paper at CIKM 2018.
  • Ioana Jivet explored how to increase self-regulation in MOOC learners through the use of an interactive learning tracker. She defended her thesis in September 2016.  Currently, Ioana is working as a PhD student at the Welten-instituut. Her thesis work contributed to a full paper at LAK 2017.
  • Yingying Bao investigated the prevalence of cheating in MOOCs. She defended her thesis in February 2017. Her thesis work contributed to a short paper at EDM 2017.
  • Jochem de Goede designed a workbench to increase the reproducibility of MOOC experiments.
  • Sambit Praharaj collaborated with researchers from Lugano to bring data analytics to the higher-education classroom. His thesis work contributed to a full paper at UMAP 2017.

We also collaborate on projects/papers with external researchers:

  • Vassileios Triglianos and Cesare Pautasso, University of Lugano.
  • Tarmo Robal, Tallinn University of Technology.
  • René Kizilcec, Stanford University.
  • Markus Krause, Telefonica.


We are regularly producing software artifacts in our lab. Here we list the more mature open-source contributions we have made:

  • SearchX is a scalable collaborative search system, developed to research large-scale search and sensemaking experiments.
  • APONE is an academic environment for online experiments. We have used in our research and teaching.
  • SIREN is a simulation framework for understanding the effects of recommender systems in online news environment.


+++ 2019 +++

Felipe Moraes, Kilia Grashoff and Claudia Hauff:
On the Impact of Group Size on Collaborative Search Effectiveness.
Accepted at the Information Retrieval Journal.

Daan Rennings, Felipe Moraes and Claudia Hauff:
An Axiomatic Approach to Diagnosing Neural IR Models.
Accepted as a full paper at the 41st European Conference on Information Retrieval.

Dimitrios Bountouridis, Jaron Harambam, Mykola Makhortykh, Monica Marrero, Nava Tintarev and Claudia Hauff:
SIREN: A Simulation Framework for Understanding the Effects of Recommender Systems in Online News Environments.
Accepted as a full paper at the 2nd ACM Conference on Fairness, Accountability, and Transparency.

+++ 2018 +++

Felipe Moraes, Sindunuraga Rikarno Putra and Claudia Hauff:
Contrasting search as a learning activity with instructor-designed learning.
Accepted as a full paper at CIKM 2018.

Sindunuraga Rikarno Putra, Kilian Grashoff, Felipe Moraes, Claudia Hauff:
On the Development of a Collaborative Search System.
Accepted as full paper at DESIRES 2018.

Yue Zhao, Tarmo Robal, Christoph Lofi, Claudia Hauff:
Can I have a Mooc2Go, please? On The Viability of Mobile vs. Stationary Learning.
Accepted as full paper at EC-TEL 2018. Best Paper Nominee.

Daniel Davis, Vasileios Triglianos, Claudia Hauff and Geert-Jan Houben:
SRLx: A Personalized Learner Interface for MOOCs.
Accepted as full paper at EC-TEL 2018.

Dan Davis, Guanliang Chen, Claudia Hauff, Geert-Jan Houben:
Activating learning at scale: A review of innovations in online learning strategies. Computers & Education 125: 327-344 (2018)

Guanliang Chen, Dan Davis, Markus Krause, Efthimia Aivaloglou, Claudia Hauff, Geert-Jan Houben:
From Learners to Earners: Enabling MOOC Learners to Apply Their Skills and Earn Money in an Online Market Place. TLT 11(2): 264-274 (2018)

Guanliang Chen, Claudia Hauff, Geert-Jan Houben:
Feature Engineering for Second Language Acquisition Modeling. BEA@NAACL-HLT 2018: 356-364

Tarmo Robal, Yue Zhao, Christoph Lofi, Claudia Hauff:
IntelliEye: Enhancing MOOC Learners' Video Watching Experience through Real-Time Attention Tracking. HT 2018: 106-114

Guanliang Chen, Jie Yang, Claudia Hauff, Geert-Jan Houben:
LearningQ: A Large-Scale Dataset for Educational Question Generation. ICWSM 2018: 481-490

Tarmo Robal, Yue Zhao, Christoph Lofi, Claudia Hauff:
Webcam-based Attention Tracking in Online Learning: A Feasibility Study. IUI 2018: 189-197

Dan Davis, René F. Kizilcec, Claudia Hauff, Geert-Jan Houben:
The half-life of MOOC knowledge: a randomized trial evaluating knowledge retention and retrieval practice in MOOCs. LAK 2018: 1-10

Dan Davis, Daniel Seaton, Claudia Hauff, Geert-Jan Houben:
Toward large-scale learning design: categorizing course designs in service of supporting learning outcomes. L@S 2018: 4:1-4:10

Sindunuraga Rikarno Putra, Felipe Moraes, Claudia Hauff:
SearchX: Empowering Collaborative Search Research. SIGIR 2018: 1265-1268

Mónica Marrero, Claudia Hauff:
A/B Testing with APONE. SIGIR 2018: 1269-1272

Yue Zhao, Tarmo Robal, Christoph Lofi, Claudia Hauff:
Stationary vs. Non-stationary Mobile Learning in MOOCs. UMAP (Adjunct Publication) 2018: 299-303

+++ 2017 +++

Yue Zhao, Christoph Lofi, Claudia Hauff:
Scalable Mind-Wandering Detection for MOOCs: A Webcam-Based Approach. EC-TEL 2017: 330-344
Best Paper Nominee.

Yingying Bao, Guanliang Chen, Claudia Hauff:
On the Prevalence of Multiple-Account Cheating in Massive Open Online Learning. EDM 2017

Dan Davis, Ioana Jivet, René F. Kizilcec, Guanliang Chen, Claudia Hauff, Geert-Jan Houben:
Follow the successful crowd: raising MOOC completion rates through social comparison at scale. LAK 2017: 454-463

Guanliang Chen, Dan Davis, Markus Krause, Claudia Hauff, Geert-Jan Houben:
Buying time: enabling learners to become earners with a real-world paid task recommender system. LAK 2017: 578-579

Yue Zhao, Dan Davis, Guanliang Chen, Christoph Lofi, Claudia Hauff, Geert-Jan Houben:
Certificate Achievement Unlocked: How Does MOOC Learners' Behaviour Change? UMAP (Adjunct Publication) 2017: 83-88

Vasileios Triglianos, Sambit Praharaj, Cesare Pautasso, Alessandro Bozzon, Claudia Hauff:
Measuring Student Behaviour Dynamics in a Large Interactive Classroom Setting. UMAP 2017: 212-220

+++ 2016 +++

Dan Davis, Guanliang Chen, Tim Van der Zee, Claudia Hauff, Geert-Jan Houben:
Retrieval Practice and Study Planning in MOOCs: Exploring Classroom-Based Self-regulated Learning Strategies at Scale. EC-TEL 2016: 57-71
Best Student Paper Award.

Vasileios Triglianos, Cesare Pautasso, Alessandro Bozzon, Claudia Hauff:
Inferring Student Attention with ASQ. EC-TEL 2016: 306-320

Dan Davis, Guanliang Chen, Claudia Hauff, Geert-Jan Houben:
Gauging MOOC Learners' Adherence to the Designed Learning Path. EDM 2016: 54-61

Guanliang Chen, Dan Davis, Claudia Hauff, Geert-Jan Houben:
Learning Transfer: Does It Take Place in MOOCs? An Investigation into the Uptake of Functional Programming in Practice. L@S 2016: 409-418
Best Paper Nominee.

Guanliang Chen, Dan Davis, Jun Lin, Claudia Hauff, Geert-Jan Houben:
Beyond the MOOC platform: gaining insights about learners from the social web. WebSci 2016: 15-24