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A self-attentive model for knowledge tracing

Paper · 2019 · Pandey

Summary

This paper addresses knowledge tracing: estimating how well a learner has mastered knowledge concepts (KCs) by predicting whether they will answer the next exercise correctly. Earlier RNN-based approaches such as DKT and DKVMN generalize poorly on sparse real-world interaction logs, where each student touches only a small share of the KCs. Pandey and Karypis propose SAKT (Self Attentive Knowledge Tracing), a Transformer-style model that uses no recurrence. Past exercise–answer pairs are embedded as keys and values, and the exercise being predicted serves as the query. Causal scaled dot-product attention selects the few earlier interactions most relevant to the current exercise. The architecture adds learned positional embeddings, multiple heads, a feed-forward layer, residual connections, layer normalization and a sigmoid output, and is trained with cross-entropy. The authors evaluate SAKT on one synthetic and four real-world datasets. It beats prior state-of-the-art models by 4.43% AUC on average and trains roughly an order of magnitude faster. The learned attention weights also reveal interpretable relations between exercises.

Key points

  • Data: Synthetic (4,000 simulated students, 50 exercises from 5 hidden concepts), ASSIST2009 (skill-builder, density 0.06), ASSIST2015 (19,917 students, 708,631 interactions, 100 skills, density 0.05), ASSISTChall and STATICS.
  • Input encoding: each interaction is encoded as a single index, e + r×E, which gives 2E possible values. Sequences are left-padded or split into chunks of length n.
  • Interpretability: on Synthetic, attention weights cluster exercises perfectly by their hidden concept, even linking exercises that sit far apart in the sequence (e.g., exercise 22 to exercise 5).
  • Ablation (d = 200, 5 heads by default): removing the attention block hurts the most. A single head is consistently worse. A second block brings no gain. Residual connections matter little, and dropping them slightly improves ASSIST2015.
  • Speed (NVIDIA Titan V): SAKT takes 1.4 s per epoch, compared with 65 s for DKT+, 45 s for DKT and 26 s for DKVMN.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Pandey. 2019. A self-attentive model for knowledge tracing. arXiv (Cornell University).

The paper itself, not this page. BibTeX from the library's record of the work. arXiv 1907.06837

@misc{pandey2019self,
  title = {{A self-attentive model for knowledge tracing}},
  author = {Pandey},
  year = {2019},
  eprint = {1907.06837},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/1907.06837}
}

References

11 references, 7 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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  4. Mohammad Khajah, Robert V Lindsey, and Michael C Mozer. 2016. How deep is knowledge tracing? arXiv preprint arXiv:1604.02416 (2016).
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  9. Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information Processing Systems. 5998–6008.
  10. Chun-Kit Yeung and Dit-Yan Yeung. 2018. Addressing two problems in deep knowledge tracing via prediction-consistent regularization. arXiv preprint arXiv:1806.02180 (2018). — [arXiv:1806.02180](https://arxiv.org/abs/1806.02180) find
  11. Jiani Zhang, Xingjian Shi, Irwin King, and Dit-Yan Yeung. Dynamic key-value memory networks for knowledge tracing. In Proceedings of the 26th International Conference on World Wide Web.

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