@article {Heift:October 2008:0958-8221:305,
	author = "Heift, Trude",
	title = "Modeling learner variability in CALL",
	journal = "Computer Assisted Language Learning",
	volume = "21",
	year = "October 2008",
	abstract = "This article describes challenges and benefits of modeling learner variability in Computer-Assisted Language Learning. We discuss the learner model of E-Tutor, a learner model that addresses learner variability by focusing on certain aspects and/or features of the learner's interlanguage. Moreover, we introduce the concept of phrase descriptors, the means by which the student model of E-Tutor captures very detailed linguistic information on the learner's performance and progress. Finally, we provide longitudinal data that emphasize the importance of monitoring fine-grained information and underline the dynamism and non-linearity of the SLA process, as also described by Dynamic Systems Theory (DST).",
	pages = "305-321(17)",
	url = "http://www.ingentaconnect.com/content/routledg/call/2008/00000021/00000004/art00002"
	doi = "doi:10.1080/09588220802343421"
}