This analysis shows growth curves for various lexical measures including Mean Length of Utterance in words (MLU-w) and Type-Token Ratio (TTR). Measures are computed over all utterances marked as belonging to a particular speaker. Note that standard CHILDES MLU is often computed over a subset of utterances and uses morphemes rather than words (see section 7.22 of the CLAN manual for more details). Also note that some measures may be confounded with file length.