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Some issues and applications in cognitive diagnosis and educational data mining. Brian W. Junker Department of Statistics Carnegie Mellon University brian@stat.cmu.edu. Presentation to the International Meeting of the Psychometric Society Tokyo Japan, July 2007. Rough Outline.
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Some issues and applications in cognitive diagnosis and educational data mining Brian W. Junker Department of Statistics Carnegie Mellon University brian@stat.cmu.edu Presentation to the International Meeting of the Psychometric Society Tokyo Japan, July 2007
Rough Outline What to do when someone comes into my office? • Cognitive Diagnosis Models (CDM’s) in Psychometrics Models: a partial review • The Assistments Project: Using CDM’s in a learning-embedded assessment system • Educational Data Mining
What are CDM’s? How are they related? • Rupp (2007), Fu & Li (2007), Junker (1999), Roussos (1994), and others • Many definitions try to characterize what the unique challenges are, but… • A simple definition of CDM: “A latent trait measurement model useful for inferences about cognitive states or processes”
“…Measurement Model useful for inferences about cognitive…” • Unidimensional Item Response Models • Multidimensional Item Response Models • Compensatory structure (e.g. Reckase, 1985, 1997) • Multiplicative structure (e.g. Embretson, 1984, 1997) • Task difficulty (LLTM; e.g. Fischer, 1995) vs. person attribute modeling (MIRT, e.g. Reckase, 1997) • (Constrained) Latent Class Models • Macready and Dayton (1977); Haertel (1989); Maris (1999); • Bayes Net Models • Mislevy et al (e.g. Mislevy, Steinberg, Yan & Almond (1999) • AI and data mining communities (more later…)
Constrained Latent Class Models • Basic ingredients • Xij is data (task/item response) • Qjk is design (Q-matrix, skills, KC’s, transfer model…) • ik is latent (knowledge state component of examinee) [ i = (i1, …,iK) is a latent class label ]
Constrained Latent Class Models • The Q matrix is the incidence matrix of a bipartite graph • All such models look like (one-layer) discrete-node Bayesian networks.
Constrained Latent Class Models • Relate ik to Xij probabilistically: • Now it looks exactly like an IRT model • What is the form of Pj(i)? • Conjunctive (many forms!) • Disjunctive (less common!) • Other??
Two simple conjunctive forms… • DINA • Examined by Junker & Sijtsma (2001) • Antecedents incl. Macready & Dayton (1977); Haertel (1989); Tatsuoka (1983, 1995) • Natural choice in educational data mining • Difficult to assign credit/blame for failure
A second simple conjunctive form • NIDA • Also examined by Junker & Sijtsma (2001) • Antecedents incl. Maris’ MCLCM (1999) • Maybe more readily assign credit/blame
A generalization of NIDA • RedRUM • *j is maximal probability of success • r*jk is penalty for each attribute not possessed • Introduced by Hartz (2002); cf. DiBello, Stout & Roussos (1995).
Compensatory & disjunctiveforms are also possible • Weaver & Junker (2004, unpubl.) • Looks like multidimensional Rasch model • Plausible for some multi-strategy settings • limited proportional reasoning domain • DINO, NIDO, … (Rupp, 2007) • Pathological gambling as in DSM-IV (Templin & Henson, 2006)
A Common Framework Mixed nonlinear logistic regression models where • is a coefficient vector; • h(i,Qj) is a vector of Qjk-weighted main effects and interactions among latent attributes: ikQjk, ik1Qjk1ik2Qjk2, ik1Qjk1ik2Qjk2ik3Qjk3 , … Henson et al. (LCDM, 2007); von Davier (GDM, 2005)
LCDM’s / GDM’s Obtain RedRUM, NIDA, DINA, DINO, etc., by constraining ’s! • Weaker constraints on ’s: conjunctive -disjunctive blends, etc. • Potentially powerful • unifying framework for many CDM’s • exploratory modeling tool
Many general frameworks, model choices and design choices • Conceptual: Fu & Li (2007); Rupp (2007) • Extensions: HO-DINA, MS-DINA and others (de la Torre & Douglas, 2004, 2005); Fusion model system (Roussos et al., in press); Bayes Nets (Mislevy et al., 1999) • Model Families: Henson et al. (2007); von Davier (2005), etc. What to do when someone comes into my office?
Example: ASSISTments Project • Web-based 8th grade mathematics tutoring system • ASSIST with, and ASSESS, progress toward Massachusetts Comprehensive Assessment System Exam (MCAS) • Main statistical/measurement goals • Predict students’ MCAS scores at end of year • Provide feedback to teachers • Ken Koedinger (Carnegie Mellon), Neil Heffernan (Worcester Polytechnic), & over 50 others at CMU, WPI and Worcester Public Schools
The ASSISTment Tutor • Main Items: Released MCAS or “morphs” • Incorrect Main “Scaffold” Items • “One-step” breakdowns of main task • Buggy feedback, hints on request, etc. • Multiple Knowledge Component (Q-matrix) models: • 1 IRT • 5 MCAS math strands • 39 MCAS standards • 77-106 “expert coded” basic skills • Goals: • Predict MCAS Scores • KC Feedback: learned/not-learned, etc.
Goal: Predicting MCAS • The exact content of the MCAS exam is not known until months after it is given • The ASSISTments themselves are ongoing throughout the school year as students learn (from teachers, from ASSISTment interactions, etc.).
Methods: Predicting MCAS • Regression approaches [Feng et al, 2006; Anozie & Junker, 2006; Ayers & Junker, 2006/2007]: • Percent Correct on Main Questions • Percent Correct on Scaffold Questions • Rasch proficiency on Main Questions • Online metrics (efficiency and help-seeking; e.g. Campione et al., 1985; Grigorenko & Sternberg, 1998) • Both end-of-year and “month-by-month” models • Bayes Net (DINA Model) approaches: • Predicting KC-coded MCAS questions from Bayes Nets (DINA model) applied to ASSISTments [Pardos, et al., 2006]; • Regression on number of KC’s mastered in DINA model [Anozie 2006]
Results: Predicting MCAS 10-fold cross-validation using:
Results: Predicting MCAS • Limits of what we can accomplish for prediction • Feng et al. (in press) estimate best-possible MAD ¼ 6from split-half experiments with MCAS • Ayers & Junker (2007) reliability calculation suggests approximate bounds 1.05· MAD · 6.46. • Best observed MAD ¼ 5.24 • Tradeoff: • Greater model complexity (DINA) can help [Pardos et al, 2006; Anozie, 2006]; • Accounting for question difficulty (Rasch), plus online metrics, does as well [Ayers & Junker, 2007]
Goal: KC Feedback • Providing feedback on • individual students • groups of students • Multiple KC (Q-matrix) models: • 1 IRT • 5 MCAS math strands • 39 MCAS standards • 106 “expert coded” basic skills • Scaffolding: Optimal measures of single KC’s? Optimal tutoring aids? • When more than one transfer model is involved, scaffolds fail to line up with at least one of them! • Use DINA Model, 106 KC’s
Results: KC Feedback • Average percent of KC’s mastered: 30-40% • February dip reflects a recording error for main questions • Monthly split-half cross-val accuracy 68-73% on average
Digression: Learning within DINA • Current model “wakes up reborn” each month; No data ! posterior falls back to prior ignoring previous response behavior. • Using last month’s posterior as this month’s prior treats previous response behavior too strongly (exchangeable with present). • Wenyi Jiang (ongoing, CMU) is looking at incorporating a Markov learning model for each KC in DINA.
Digression: Question & KC Model Characteristics Main Item: Guess gj (posterior boxplots) Which graph contains the points in the table? Slip sj (posterior boxplots) Scaffolds: • Quadrant of (-2,-3)? • Quadrant of (-1,-1)? • Quadrant of (1,3)? • [Repeat main]
Some questions driven by ASSISTments • Different KC models for different purposes seem necessary. • How deeply meaningful are the KC’s? • Q-matrix is QC! task design; what about task ! examinee design? • Henson & Douglas (2005) provide recent developments in KL-based item selection for CDM’s • Most settings have designed, undesigned missingness • Interactions between assignment design and learning • How close to right does the CDM have to be? • Douglas & Chui (2007) have started mis-specification studies • Perhaps the Henson/von Davier frameworks can help? • For ASSISTments and other settings, this is a sparse data model fit question! • How to design and improve the KC model?
Some options for designing/improving KC model • Expert Opinion, Iterations • Rule space method (Tatsuoka 1983, 1995) • Directly minimizing ij||ij – Xij|| as a function of Q (Barnes 2005, 2006): Boolean regression & variable generation/selection [related: Leenen et al., 2000] • Learning Factors Analysis (Cen, Koedinger & Junker 2005, 2006): learning curve misfit is a better clue to improving the Q-matrix than static performance misfit
From www.educationaldatamining.org • Educational Data Mining Workshop, at the 13th International Conference on Artificial Intelligence in Education (AI-ED). Los Angeles, California, USA. July 9, 2007. • Workshop on Educational Data Mining, at the 7th IEEE International Conference on Advanced Learning Technologies. Niigata, Japan. During the period July 18-20, 2007. • Workshop on Educational Data Mining at the 21st National Conference on Artificial Intelligence (AAAI 2006). Boston, USA. July 16-17, 2006. • Workshop on Educational Data Mining at the 8th International Conference on Intelligent Tutoring Systems (ITS 2006). Jhongli, Taiwan, 2006. • Workshop on Educational Data Mining at the 20th National Conf. on Artificial Intelligence (AAAI 2005). Pittsburgh, USA, 2005.
From AAAI 2005 • Evaluating the Feasibility of Learning Student Models from Data Anders Jonnson, Jeff Johns, Hasmik Mehranian, Ivon Arroyo, Beverly Woolf, Andrew Barto, Donald Fisher, and Sridhar Mahadevan • Topic Extraction from Item-Level Grades Titus Winters, Christian Shelton, Tom Payne, and Guobiao Mei • An Educational Data Mining Tool to Browse Tutor-Student Interactions: Time Will Tell! Jack Mostow, Joseph Beck, Hao Cen, Andrew Cuneo, Evandro Gouvea, and Cecily Heiner • A Data Collection Framework for Capturing ITS Data Based on an Agent Communication Standard Olga Medvedeva, Girish Chavan, and Rebecca S. Crowley • Data Mining Patterns of Thought Earl Hunt and Tara Madhyastha • The Q-matrix Method: Mining Student Response Data for Knowledge Tiffany Barnes • Automating Cognitive Model Improvement by A*Search and Logistic Regression Hao Cen, Kenneth Koedinger, and Brian Junker • Looking for Sources of Error in Predicting Student’s Knowledge Mingyu Feng, Neil T. Heffernan, and Kenneth R. Koedinger • Time and Attention: Students, Sessions, and Tasks Andrew Arnold, Richard Scheines, Joseph E. Beck, and Bill Jerome • Logging Students’ Model-Based Learning and Inquiry Skills in Science Janice Gobert, Paul Horwitz, Barbara Buckley, Amie Mansfield, Edmund Burke, and Dimitry Markman
Educational Data Mining • Often very clever algorithms & data management, not constrained by quant or measurement traditions • A strength (open to new approaches) • A weakness (re-inventing the wheel, failing to see where a well-understood difficulty lies, etc)
Conclusions? Questions… • Lots of options for CDM’s, not yet much practical experience beyond “my model worked here” • Significant design questions remain, and seem to admit quantitative solutions • Need to be connected to real projects • real world constraints • real world competitors in EDM • It would be mutually advantageous to join with EDM and draw EDM (partially?) into our community… Can we do it? Do we want to?
END (references follow)
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