Snow, E. L., Allen, L. K., Jacovina, M. E., Crossley, S. A., Perret, C. A., & McNamara, D. S. (2016). Keys to Detecting Writing Flexibility Over Time: Entropy and Natural Language Processing. Journal of Learning Analytics, 2(3), 40-54. https://doi.org/10.18608/jla.2015.23.4