SLA Topics   Vivian Cook 
MLU
(Mean Length
of Utterance)
in Morphemes

1. Record enough natural speech to yield at least one hundred consecutive
             utterances after stages 2 to 3 below.

2. Transcribe the speech.

3. Eliminate:
              — all utterances where it is unclear what the child said.
              — exclamations, mm, oh, etc, except when they form the entire utterance
              — false starts, want - want drink

4. Count the number of morphemes, both content and grammatical, counting
              as a single morpheme:
              — compound words, choo-choo, birthday etc
              — words with ‘ie/y’, mummy, doggie
              — irregular past tense, went
              but including as separate morphemes:
              · auxiliaries; will, , is, ’s, have, ’ve, etc
              · all inflected endings ‘-s’, ‘-ed’, etc

5. Divide the total by the number of utterance to get the MLU in morphemes.

L1 sources: Roger Brown, Paul Fletcher