Associate Professor of Information
Associate Professor of Electrical Engineering and Computer Science
University of Michigan School of Information and
College of Engineering (affiliate)
Email: kevynct AT umich . edu
School of Information
3344 North Quad
105 S. State Street
Ann Arbor, MI 48109-1285
My lab explores algorithms and interfaces for intelligent information systems that optimally connect people with information, especially for educational goals. Examples include search engines that can deliver the right kind of personalized information at the right time, and intelligent tutoring systems that learn when and how to be most helpful in teaching a particular student. Building effective, reliable systems like these will require new theoretical, algorithmic, and methodological advances in multiple research areas, including machine learning, optimization, information retrieval, and human-computer interaction. My current research is centered on education, but I'm also interested in mobile and health-related applications.
I currently work with the following graduate students:
Sept 1 2019: Starting Fall 2019 I will be based in France at Inria, France's national research institute for computer science. I am not available at the University of Michigan campus and not accepting new students into my research group. Also, please expect likely delays in email replies.
June 30 2019: I'll be a keynote speaker at LILE 2019, Learning and Education with Web Data, collocated with ACM WebSci 2019, Boston.
July-August 2018: Visiting researcher at Microsoft Research AI.
Feb 12-13, 2018: Visiting RMIT Computer Science, Melbourne, Australia.
Feb 5 2018: Participating in the VC/Industry Day panel at WSDM 2018 (Los Angeles) on academic vs industry careers.
Oct 27 2017: I'll be presenting recent research at Carnegie Mellon's LTI Colloquium on Fri. Oct 27.
Feb 2017: Here's the homepage for our Dagstuhl Seminar on Searching as Learning, co-organized with Claudia Hauff and Preben Hansen.
M. DeJonckheere, L. Nichols, V.G. Vydiswaran, X. Zhao, K. Collins-Thompson, K. Resnicow, T. Chang. Using Text Messaging, Social Media, and Interviews to Understand What Pregnant Youth Think about Weight Gain During Pregnancy. J. Medical Inform. Formative Research. 2019 Apr 1;3(2):e11397. doi: 10.2196/11397
Jin Shang, Mingxuan Sun, and Kevyn Collins-Thompson. Demographic Inference via Knowledge Transfer in Cross-Domain Recommender Systems. Proceedings of ICDM 2018. Singapore, 2018, pp. 1218-1223.doi: 10.1109/ICDM.2018.00162
Nalin Chhibber, Rohail Syed, Mengqiu Teng, Joslin Goh, Kevyn Collins-Thompson and Edith Law. Human Perception of Surprise: A User Study. SIGIR 2018 CompS18 Workshop on Computational Surprise. (pdf)[MIDAS Poster Award]
Kevyn Collins-Thompson, Qiaozhu Mei, Brian D. Davison, Yiqun Liu, Emine Yilmaz:
The 41st International ACM SIGIR Conference on Research & Development in Information Retrieval, SIGIR 2018, Ann Arbor, MI, USA, July 08-12, 2018. ACM 2018
R. Syed, K. Collins-Thompson. Exploring Document Retrieval Features Associated with Improved Short- and Long-term Vocabulary Learning Outcomes. Proceedings of ACM CHIIR 2018. (Full paper) [Best Student Paper Award]
R. Syed and K. Collins-Thompson. 2017. Retrieval Algorithms Optimized for Human Learning. In Proceedings of the 40th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR '17). ACM, New York, NY, USA, 555-564. (pdf)(Full paper)
K. Collins-Thompson, P. Hansen, C. Hauff. Search as Learning: Report from Dagstuhl Seminar 17092, Feb. 2017. (pdf)
H. Choi, Z. Wang, C. Brooks, K. Collins-Thompson, B.G. Reed, D. Fitch. Social work in the classroom? A tool to evaluate topical relevance in student writing. Proceedings of Educational Data Mining (EDM 2017), Wuhan, China. (pdf) (short paper)
S. Nam, G. Frishkoff, K. Collins-Thompson. Predicting Students' Disengaged Behaviors in an Online Meaning-Generation Task. IEEE Transactions on Learning Technologies.
S. Nam, G. Frishkoff, K. Collins-Thompson. Modeling Off-task Behaviors in a Meaning-Generation Task. In Measurement in Digital Environments White Paper Series, SRI. (pdf)
R. Syed, K. Collins-Thompson. Optimizing Search Results for Human Learning Goals.
Information Retrieval Journal (Special Issue on Searching as Learning), 2017.
S. Nam, G. Frishkoff, K. Collins-Thompson. Predicting Short- and Long-Term Student Learning with a Vocabulary Tutoring System via Semantic Features of Definition Responses
Proceedings of Educational Data Mining (EDM 2017), Wuhan, China. pp. 80-87. (Full paper)
H. Choi, C. Brooks, K. Collins-Thompson. What does student writing tell us about their thinking on social justice? Proceedings of the 7th Int'l Conf on Learning Analytics and Knowledge (LAK 2017), Vancouver, Canada. (Poster)
E. Schumacher, M. Eskenazi, G. Frishkoff, K. Collins-Thompson. Predicting the Relative Difficulty of Single Sentences With and Without Surrounding Context. Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing (EMNLP 2016), pages 1871-1881.(pdf)
R. Syed, K. Collins-Thompson. Optimizing Search Results for Educational Goals: Incorporating Keyword Density as a Retrieval Objective. Proceedings of the SIGIR 2016 Workshop on Searching as Learning (SAL 2016). Pisa, Italy. (pdf)
R. Burton, K. Collins-Thompson. User Behavior in Asynchronous Slow Search. Proceedings of ACM SIGIR 2016. Pisa, Italy. (Full paper) (pdf)
R. Burton, K. Collins-Thompson. Understanding User Adjustment to Slow Search. Proceedings of the ACM CHIIR 2016 Workshop on System and User-Centered Evaluation Approaches in Interactive Information Retrieval. CEUR-WS Proceedings Series. (pdf)
T. Chang, B. Varma, T. Shull, M. Moniz, L. Kohatsu, M. Plegue, K. Collins-Thompson. "Crowdsourcing and the Accuracy of Online Information Regarding Weight Gain in Pregnancy". Journal of Medical Internet Research, 18(4):e81, April 2016. (link)
Frishkoff, G. A., Collins-Thompson, K., Hodges, L., & Crossley, S. (2016). Accuracy feedback improves word learning from context: Evidence from a meaning-generation task. Reading and Writing, 29(4), 609-632. doi:10.1007/s11145-015-9615-7. (link)
Y. Kim, K. Collins-Thompson, J. Teevan. "Using the Crowd to Improve Search Result Ranking and the Search Experience". ACM Transactions on Intelligent Systems and Technology. Vol 9, No. 4. 2016. (pdf)
K. Collins-Thompson, S-Y. Rieh, C. Haynes, R. Syed. Assessing Learning Outcomes in Web Search: A Comparison of Tasks and Query Strategies (Full paper). ACM SIGIR Conference on Human Information Interaction and Retrieval (CHIIR 2016). Chapel Hill, NC. March 2016. (pdf)
S.J. Nam, K. Collins-Thompson, G. Frishkoff. (To appear) Modeling Real-time Performance on a Meaning-Generation Task. (Short paper). Annual Meeting of the American Educational Research Association (AERA 2016), Washington DC, April 2016.
S.Y. Rieh, K. Collins-Thompson, P. Hansen, H-Y Lee. Towards searching as a learning process: a review of current perspectives and future directions. Journal of Information Science, 2015. (link)
J. Karlgren, J. Callin, K. Collins-Thompson, A.C. Gyllensten, A. Ekgren, D. Jurgens, A. Korhonen, F. Olsson, M. Sahlgren, H. Schütze. Evaluating learning language representations. Proceedings of CLEF 2015. (pdf)
Wu DT, Hanauer DA, Mei Q, Clark PM, An LC, Proulxe J, Zeng QT, Vydiswaran VGV, Collins-Thompson K, Zheng K. Assessing the readability of ClinicalTrials.gov. J. American Medical Informatics Assoc. 2015. (link)
Frishkoff, G., Collins-Thompson, K., Nam, S.J., Hodges, L., & Crossley, S. (To appear) Dynamic Support of Contextual Vocabulary Acquisition for Reading (DSCoVAR): An intelligent tutoring system for contextual word learning. In S.A. Crossley & D.S. McNamara (Eds.), Adaptive Educational Technologies for Literacy Instruction. Taylor & Francis, Routledge:NY.
M. Shokouhi, M. Sloan, P.N. Bennett, K. Collins-Thompson, S. Sarkizova. Contextual Disambiguation for Query Suggestion and Blending. Proceedings of WWW 2015. pg. 971-980. (pdf)
L. Hodges, G. Frishkoff, K. Collins-Thompson. (Conference abstract) Scaffolding of Support and Individual Differences in Contextual Word Learning. The 22nd Annual Meeting of the Society for the Scientific Study of Reading, 2015. (Oral presentation)(link)
S. Nam, K. Collins-Thompson, G. Frishkoff, L. Hodges. (Conference abstract) Measuring Real-time Student Engagement in Contextual Word Learning. The 22nd Annual Meeting of the Society for the Scientific Study of Reading, 2015. (Poster presentation)(link)
P.N. Bennett, K. Collins-Thompson, D. Kelly, R.W. White, Y. Zhang (eds.). Special Issue of ACM TOIS on Contextual Search and Recommendation (In press.), Vol. 33, Issue 1 (Jan. 2015) (pdf)
K. Collins-Thompson, C. Macdonald, P. N. Bennett, F. Diaz, E. Voorhees. TREC 2014 Web Track Overview. NIST Special Publication SP 500-308, Nov 2014. (pdf)
K. Collins-Thompson. Computational assessment of text readability: a survey of current and future research. In: François, Thomas and Delphine Bernhard (eds.), Recent Advances in Automatic Readability Assessment and Text Simplification. Special issue of International Journal of Applied Linguistics 165:2 (2014). (pp. 97-135) (Working paper here)
K. Raman, P.N. Bennett, K. Collins-Thompson. Understanding Intrinsic Diversity in Web Search: Improving Whole-Session Relevance. ACM Transactions on Information Systems (TOIS), Oct. 2014. (pdf)
S.Y. Rieh, J. Gwizdka, L. Freund, K. Collins-Thompson. Searching as Learning: Novel Measures for Information Interaction Research. Proceedings of the American Society for Information Science and Technology 51(1): 1-4.
J. Teevan, K. Collins-Thompson, R. White, S. Dumais. Slow Search. Communications of the ACM 57(8): 36-38 (2014) August 2014. (link)
U.S. Patent 8,719,249. Query classification. Bennett; Paul N., Chickering; David M., Collins-Thompson; Kevyn B., Dumais; Susan T., Liebling; Daniel J.
U.S. Patent 8,700,544. Functionality for Personalizing Search Results. Sontag; David A., Collins-Thompson; Kevyn B., Bennett; Paul N., White; Ryen W., Dumais; Susan T.
K. Collins-Thompson, P. N. Bennett, F. Diaz, C. Clarke, E. Voorhees. TREC 2013 Web Track Overview. NIST Special Publication, Feb 2014. (pdf)
Y. Kim, K. Collins-Thompson, J. Teevan. Crowdsourcing for Robustness in Web Search. NIST Special Publication, Nov. 2013. (pdf)
D. Sontag, K. Collins-Thompson, P. N. Bennett, R. W. White, S. Dumais, B. Billerbeck. Personalization via Probabilistic Adaptation. NIPS 2013 Workshop on Personalization, Dec. 2013. (pdf)
A. Ali, K. Collins-Thompson. Robust Cost-Sensitive Confidence-Weighted Classification. Proceedings of the 8th Workshop on Optimization-Based Techniques for Emerging Data Mining Problems. (OEDM 2013) Dallas, Dec. 2013. (pdf)
J. Teevan, K. Collins-Thompson, R. White, S. Dumais, Y. Kim. Slow Search: Information retrieval without time constraints. Proceedings of HCIR 2013. (pdf)
K. Raman, P.N. Bennett, K. Collins-Thompson. Toward Whole-Session Relevance: Exploring Intrinsic Diversity in Web Search. Proceedings of SIGIR 2013. 463-472. (pdf)[SIGIR Best Student Paper]
F. Raiber, K. Collins-Thompson, O. Kurland. Shame to be Sham: Addressing Content-Based Grey Hat Search Engine Optimization. (Short paper) Proceedings of SIGIR 2013. 1013-1016.
C. Eickhoff, A. de Vries, K. Collins-Thompson. Copulas for Information Retrieval. Proceedings of SIGIR 2013. 663-672. (pdf)
C. Eickhoff, K. Collins-Thompson, P.N. Bennett, S. Dumais. Designing Human-Readable User Profiles for Search Evaluation. Proceedings of ECIR 2013. 701-705. (Short paper) (pdf)
C. Eickhoff, K. Collins-Thompson, P.N. Bennett, S. Dumais. Personalizing Atypical Web Search Sessions. Proceedings of WSDM 2013. 285-294. (Selected for plenary session.)(pdf)
X. Chen, P.N. Bennett, K. Collins-Thompson, E. Horvitz. Pairwise Ranking Aggregation in a Crowdsourced Setting. Proceedings of WSDM 2013. 193-202.(pdf)
K. Collins-Thompson, G. Frishkoff, S. A. Crossley. Definition Response Scoring with Probabilistic Ordinal Regression. Proceedings of ICCE 2012, Singapore, Nov. 2012.(pdf)
L. Wang, P.N. Bennett, K. Collins-Thompson. Robust ranking models via risk-sensitive optimization. Proceedings of SIGIR 2012. (pdf)[SIGIR Best Paper Honorable Mention]
G. Frishkoff, K. Collins-Thompson, C. Perfetti, S. Crossley. Incremental and adaptive word learning from context. SSSR 2012, the Conference of the Society for the Scientific Study of Reading, Montreal, July 2012. Abstract.
J. Kim, K. Collins-Thompson, P. N. Bennett, S. Dumais. Characterizing Web Content, User Interests, and Search Behavior by Reading Level and Topic. Proceedings of WSDM 2012. (pdf)
D. Sontag, K. Collins-Thompson, P. N. Bennett, R. W. White, S. Dumais, B. Billerbeck. Probabilistic Models for Personalizing Web Search. Proceedings of WSDM 2012. (pdf)
K. Collins-Thompson, P. N. Bennett, R. W. White, S. de la Chica, D. Sontag. Personalizing Web Search Results by Reading Level. Proceedings of the Twentieth ACM International Conference on Information and Knowledge Management (CIKM 2011). Glasgow, Scotland. Oct. 2011. (pdf)
P. Kidwell, G. Lebanon, K. Collins-Thompson. Statistical Estimation of Word Acquisition with Application to Readability Prediction. Journal of the American Statistical Association. 106(493):21-30, 2011. (pdf)
K. Collins-Thompson. "Improving information retrieval with reading level prediction." SIGIR 2011 Workshop on Enriching Information Retrieval. Beijing, July 2011. (pdf)
G. Frishkoff, C. Perfetti, and K. Collins-Thompson. "Predicting robust vocabulary growth from measures of incremental learning". Scientific Studies of Reading, 15(1), 71-91. January 2011.
J. Dillon and K. Collins-Thompson. A unified optimization framework for robust pseudo-relevance feedback algorithms. Proceedings of the Nineteenth ACM International Conference on Information and Knowledge Management (CIKM 2010), Toronto, Canada. (CIKM Student Travel Award Paper) (pdf)
M. Heilman, K. Collins-Thompson, M. Eskenazi, A. Juffs, L. Wilson. "Personalization of reading passages improves vocabulary acquisition." International Journal of Artificial Intelligence in Education, 20(1), 2010. (pdf)
J. Huang, N. Koudas, G. Jones, X. Wu, K. Collins-Thompson, and A. An. (eds.) Proceedings of the Nineteenth ACM International Conference on Information and Knowledge Management (CIKM 2010), ACM Press, New York.
K. Collins-Thompson and J. Dillon. Controlling the search for expanded query representations by constrained optimization in latent variable space. SIGIR 2010 Workshop on Query Representation and Understanding.(pdf)
Frishkoff, G. A., Perfetti, C. A., & Collins-Thompson, K. (2010). Lexical quality in the brain: ERP evidence for robust word learning from
context. Developmental Neuropsychology, 35(4), 1-28. [details]
M. Sun, G. Lebanon, and K. Collins-Thompson. "Visualizing Differences in Web Search Algorithms using the Expected Weighted Hoeffding Distance". Proceedings of WWW 2010, Raleigh, NC, U.S.A. pg 931-940. (pdf)  [bibtex]
K. Collins-Thompson, P.N. Bennett. "Predicting query performance via classification", Proceedings of ECIR 2010, Milton Keynes, UK. pg 140-152. (pdf)  [bibtex]
K. Collins-Thompson. "Reducing the risk of query expansion via robust constrained optimization". Proceedings of the Eighteenth International Conference on Information and Knowledge Management (CIKM 2009). ACM. Hong Kong. pg. 837-846.(pdf)  [bibtex]
K. Collins-Thompson. "Accounting for stability of retrieval algorithms using risk-reward curves". Proceedings of SIGIR 2009 Workshop on the Future of Evaluation in Information Retrieval, Boston. pg. 27-28.(pdf)
M. Sun, G. Lebanon, and K. Collins-Thompson. Visualizing Spatial Proximity of Search Algorithms, NIPS Workshop on Learning with Ordering. (Poster abstract), 2009. (pdf)
K. Collins-Thompson. "Robust word similarity estimation using perturbation kernels". Proceedings of the International Conference on Theoretical Information Retrieval (ICTIR) 2009, Cambridge, U.K. pg. 265-272.(pdf)  [bibtex]
P. Kidwell, G. Lebanon, K. Collins-Thompson. "Statistical estimation of word acquisition with application to readability prediction". Proceedings of Empirical Methods in Natural Language Processing (EMNLP) 2009, Singapore. (pdf)
K. Collins-Thompson, P. N. Bennett. "Estimating query performance using class predictions". Proceedings of the Thirty-second Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2009), Boston. pg. 672-673. (Poster description) (pdf)  [bibtex]
K. Collins-Thompson. "Estimating robust query models with convex optimization". Advances in Neural Information Processing Systems 21 (NIPS), 2008. pg. 329-336.(pdf)   [bibtex]
K. Collins-Thompson. "Robust model estimation methods for information retrieval". Ph.D. thesis (LTI Technical Report CMU-LTI-08-010) Carnegie Mellon University, 2008.
G. Frishkoff, K. Collins-Thompson, C. Perfetti, J. Callan. Measuring incremental changes in word knowledge: Experimental validation and implications for learning and assessment. Behavior Research Methods, Vol. 40, No. 4. pp. 907-925. (pdf)  [pubmed]
M. Heilman, K. Collins-Thompson and M. Eskenazi. "An analysis of statistical models and features for reading difficulty prediction." ACL 2008 BEA Workshop on Innovative Use of NLP for Building Educational Applications. Columbus, Ohio. (pdf)
K. Collins-Thompson and J. Callan. "Estimation and use of uncertainty in pseudo-relevance feedback." Proceedings of the Thirtieth Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2007), Amsterdam. (pdf)  [bibtex]
K. Collins-Thompson and J. Callan. "Automatic and human scoring of word definition responses." Proceedings of the NAACL-HLT 2007 Conference. Rochester, U.S.A. pp. 476-483. (pdf)  [bibtex]
K. Collins-Thompson. Optimization methods for query model estimation: applying portfolio theory to mitigate risk in information retrieval. CMU DIR Group Technical Report 2007-09-03. Abstract
M. Heilman, K. Collins-Thompson, J. Callan and M. Eskenazi. "Combining lexical and grammatical features to improve readability measures for first and second language texts." Proceedings of the NAACL-HLT 2007 Conference. Rochester, U.S.A. pp. 460-467. (pdf)  [bibtex]
M. Heilman, K. Collins-Thompson, J. Callan, and M. Eskenazi. Classroom success of an Intelligent Tutoring System for lexical practice and reading comprehension. Proceedings of Interspeech 2006. Pittsburgh, U.S.A. abstract
A. Juffs, L. Wilson, M. Eskenazi, J. Callan, J. Brown, K. Collins-Thompson, M. Heilman, T. Pelletreau, and J. Sanders. (2006) "Robust learning of vocabulary: investigating the relationship between learner behaviour and the acquisition of vocabulary" (poster). The 40th Annual TESOL Convention and Exhibit (TESOL 2006).
K. Collins-Thompson and J. Callan. Query expansion using random walk models. Proceedings of the Fourteenth International Conference on Information and Knowledge Management (CIKM'05). ACM. Bremen, Germany. (CIKM Student Travel Award Paper) (pdf)  [bibtex]
K. Collins-Thompson, J. Callan. Predicting reading difficulty with statistical language models. Journal of the American Society for Information Science and Technology. Vol. 56, No. 13, 1448-1462.  [bibtex]
K. Collins-Thompson, P. Ogilvie and J. Callan. Initial results with structured queries and language models on half a terabyte of text. Proceedings of TREC 2004, National Institute of Standards and Technology, special publication. (pdf)
K. Collins-Thompson and J. Callan. A language modeling approach to predicting reading difficulty. Proceedings of HLT / NAACL 2004, Boston, USA, May 2004. pp 193-200. (pdf)  [bibtex]
K. Collins-Thompson and J. Callan. Information retrieval for language tutoring: an overview of the REAP project (poster description), Proceedings of SIGIR 2004, Sheffield, UK. July 2004. (pdf)  [bibtex]
K. Collins-Thompson, E. Terra, J. Callan, and C. Clarke. The effect of document retrieval quality on factoid question-answering performance (poster description), Proceedings of SIGIR 2004, Sheffield, UK. July 2004. (pdf)  [bibtex]
J. Zhang, A. Toth, K. Collins-Thompson, and A. Black. Prominence prediction for super-sentential prosodic modeling based on a new database, ISCA Synthesis Workshop, Pittsburgh, USA, June 2004.
E. Nyberg, T. Mitamura, J. Callan, J. Carbonell, R. Frederking, K. Collins-Thompson, L. Hiyakumoto, Y. Huang, C. Huttenhower, S. Judy, J. Ko, A. Kupsc, L. V. Lita, V. Pedro, D. Svoboda, and B. Van Durme. (2004.) "The JAVELIN question-answering system at TREC 2003: A multi-strategy approach with dynamic planning." Proceedings of the 2003 Text REtrieval Conference (TREC 2003). National Institute of Standards and Technology, special publication. (pdf)
U.S. Patent 6,735,335. M. Liu, K. Collins-Thompson, D. Lawton. Method and apparatus for discriminating between documents in batch scanned document files. May 2004.
U.S. Patent 6,687,697. K. Collins-Thompson, C. Schweizer. System and method for improved string matching under noisy channel conditions. Feb. 2004.
K. Collins-Thompson, P. Ogilvie, Y. Zhang, and J. Callan. Information filtering, novelty detection, and named-page finding. In Proceedings of the 2002 Text REtrieval Conference (TREC 2002). National Institute of Standards and Technology, special publication. 107 - 118.(pdf)
E. Nyberg, T. Mitamura, J. Carbonell, J. Callan, K. Collins-Thompson, K. Czuba, M. Duggan, L. Hiyakumoto, N. Hu, Y. Huang, J. Ko, L. Lita, S. Murtagh, V. Pedro, D. Svoboda. The JAVELIN Question-Answering System. In Proceedings of TREC 2002. NIST, special publication. 128 - 137.
Reviewer, ACM Transactions on Information Systems; ACM Transactions on the Web; IEEE Transactions on Knowledge and Data Engineering; Information Processing and Management; Foundations and Trends in Information Retrieval; Transactions on Audio, Speech, and Language Processing; Journal of the American Society for Information Science and Technology.
WSDM 2013 Crowdsourced Pairwise Preferences for Readability (.csv file, 9.1Mb): 13857 judged pairs (trusted and untrusted), ~50-word text passages, grades 1-12. Column descriptions are here.
If you use this dataset, please cite: X. Chen, P.N. Bennett, K. Collins-Thompson, E. Horvitz. Pairwise Ranking Aggregation in a Crowdsourced Setting. Proceedings of WSDM 2013. 193-202.
HLT 2004 Readability: Unigram Language Models. Because a significant part of the corpus used for this paper (Web pages or text passages labeled by grade level) contains licensed copyrighted content, we are unable to redistribute the dataset in its original form. However, this folder contains files with frequency counts computed on the entire dataset for the twelve categories of labeled documents used in the HLT 2004 paper, corresponding to material at each of the U.S. elementary school grades 1 through 12 (indexed as 0 to 11). There is also a background English model file. With these raw unigram counts, plus some smoothing as described in the paper, the grade-level language models used for the classifier can be derived. If you use this data, please cite:
K. Collins-Thompson and J. Callan. A language modeling approach to predicting reading difficulty. Proceedings of HLT / NAACL 2004, Boston, USA, May 2004. 193-200.