MLU and N:V ratio guidelines
• The formula is: 𝑡𝑜𝑡𝑎𝑙 𝑚𝑜𝑟𝑝ℎ𝑒𝑚𝑒𝑠
• If there is a false start or disfluency, discount this, and count only the final utterance
• “xxx” or “yyy” means “unintelligible”. If the utterance contains this, leave it out of the MLU count.
o BUT words in such utterances can be counted as words that the child knows for the N:V
• If there is a 0 next to a word, this means that the word is missing from the child’s utterance. So do
not include it in your count of the morphemes in that utterance!
• This the ratio of the number of unique nouns in the child’s speech to the number of unique verbs
• If a word has “[?]” after it, give them the benefit of the doubt and count it as a word the child
• Proper names should be counted as nouns
• Pronouns are not nouns – pronouns are function words and should be counted as “other”
• Copulas and auxiliaries should not be counted as verbs – only lexical verbs should be included in the
• There is some flexibility as to words which could be either a verb or a noun – you will not be
penalised for the decision you make. However, if you are unsure, you can go with the category
given to that word in the %mor tier by the transcriber.
• Noun to verb ratio should be expressed in the form N:V, e.g. 8:4 (which can be simplified → 2:1).
Example: Table 2
• Utterances highlighted in green CAN be counted in MLU
• Utterances highlighted in orange CANNOT be counted in MLU
• Utterances highlighted in green or orange can be used in the tabulation of different parts of
speech, and calculation of N:V ratio.
• L.17 “drink” could be a verb or a noun. I have chosen to categorise it as a verb (Tables 2 & 3),
assuming the target utterance is “The rabbit wants to drink.” But you could justify counting it as a
noun if you assume the target utterance is “The rabbit wants a drink”
• Note that even if the child repeats an utterance, each one can be counted in MLU – so l.18-19
would be counted as two utterances in the MLU calculation (Table 1)
• N:V ratio is 2:3 (Table 3)
• Line 11: “Ra-“ is a false start and gets ignored, and we only look at the final utterance, ”rabbit”
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