@article{sparsefactoranalysisforlearningand,
  title = {Sparse Factor Analysis for Learning and Content Analytics},
  author = {Andrew S. Lan and Andrew E. Waters and Christoph Studer and Richard G. Baraniuk},
  year = {2013},
  eprint = {1303.5685},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1303.5685v2},
}