I Although originally designed to assess syntactic development in the written work of children learning their first language, the T unit has been widely used in second language research and is particularly useful for oral production (see, for example, Beebe, 1983; Gaies, 1980; Larsen-Freeman, 1983). A variety of measures of complexity have been based on the T unit, e.g., words per T unit, words per error-free T unit, and clauses per T unit (Gaies, 1980; Hunt, 1965; Larsen-Freeman, 1983). Nevertheless, for the description of syntactic complexity in the writing of adult second language learners, sentence-based analyses may be superior. Hunt (1965) introduced the T unit, or minimal terminable unit, to measure development of sentences in the writing of grade-school children. Each T unit contains one independent clause and its dependent clauses. Hunt (1970) described T units as "the shortest units into which a piece of discourse can be cut without leaving any sentence fragments as residue" (p. 189). A sentence has two (or more) T units when independent clauses (with subjects and finite verbs) are conjoined as in Example 1, but a single T unit when one or more clauses are embedded in an independent clause as in Example 2:
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