When is T-unit analysis typically used?

• A. From birth
• B. Starting at age 4 or when MLU exceeds 4.0
• C. Only after age 10
• D. During infancy

Answer: (B)

T-unit analysis is a way to assess syntactic complexity in connected speech by dividing a language sample into T-units, each being one main clause plus any attached subordinate clauses. This method is especially helpful once children move beyond the very early years, because mean length of utterance (MLU) continues to rise in preschoolers but then plateaus around age four. When MLU reaches about four morphemes per utterance, T-units provide a more stable, informative measure of grammar and sentence structure than MLU alone. So, it’s typically used starting at age four or when MLU exceeds four, to capture later-developing aspects like subordination and elaboration. The other options don’t fit the developmental timing, as T-unit analysis isn’t used in infancy or birth, and it isn’t reserved only for after age ten.