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TNW

Total Number of Words (TNW)

TNW is the raw word count in a language sample — the denominator behind almost every other LSA metric and a useful productivity index in its own right.

What TNW measures

Total Number of Words is exactly what the label suggests — every word produced across all complete, intelligible utterances in the sample, counted with inflections as separate tokens. TNW is both a metric on its own (it indexes verbal productivity or "talkativeness") and the denominator for derived measures such as TTR and MATTR. It is easy to compute, completely automated in any transcription tool, and does not require grammatical judgement.

Formula

TNW = Σ all word tokens across intelligible utterances

Normative ranges and benchmarks

  • Age 5;0, 10-minute conversation — 300 – 500 words
  • Age 8;0, 10-minute conversation — 500 – 850 words
  • Age 12;0, 10-minute conversation — 700 – 1100 words
  • Expressive-language-disordered children often cluster at the low end even when MLU is in range
  • TNW drops sharply in children with pragmatic language impairment regardless of their grammatical ability

Normative bands are central estimates drawn from the cited literature. Individual variation is wide — always cross-reference against the source paper and your assessment's own manual before quoting a cut-score in a report.

Clinical use

Because TNW is dependent on sample length and topic, its diagnostic value lives in comparison, not in an absolute number. The most common use is an intra-child comparison across two conditions — story retell vs conversation, preferred topic vs non-preferred topic — to identify the contexts in which a child is clamming up. TNW is also the first number to look at when a clinician suspects selective mutism, social-pragmatic language disorder, or emerging autism spectrum symptomatology, because those presentations show up as low volume first and "grammar" second. Always report TNW alongside the sample duration — a 200-word sample taken in a 3-minute probe is not the same as 200 words across 20 minutes.

“Two identical transcripts with identical MLU can come from two very different children if one produced the sample in 45 utterances and the other needed 90. TNW-per-minute is the variable that catches pragmatic under-production.”
Volume catches what length misses

Free tools that compute TNW

Language Sample Worksheet

Free printable and fillable language sample analysis worksheet for speech-language pathologists. Five columns (utterance #, transcription, morpheme count, grammatical Y/N, notes), configurable row count up to 100 utterances, browser print produces a clean PDF, and an inline running summary tracks total utterances, total morphemes, and rolling MLU as you fill it in.

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MLU Calculator

Paste a language sample and get Mean Length of Utterance in morphemes and words, total utterances, total morphemes, and the matching Brown's stage. Implements Brown (1973) morpheme counting rules and runs entirely in your browser.

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Conversation Turn Analyzer

Free interactive conversation turn analyzer for school-based and clinic speech-language pathologists analysing child-partner dialogue transcripts. Paste a transcript with speaker tags (e.g. C: and P:) and mark each child turn as [on] or [off] for topic maintenance. The analyzer returns turns per speaker, average turn length, longest / shortest turn, total speaker-to-speaker turn switches, the child topic-maintenance ratio, a four-tier topic-maintenance classification (poor, emerging, adequate, strong), and a three-tier turn-balance classification (partner-dominant, balanced, child-dominant) in under five minutes. Tier thresholds are derived from Fey (1986), Brinton & Fujiki (1989), Mentis & Prutting (1991), and Timler (2008). Built for school SLPs, clinic SLPs, autism-assessment teams, graduate SLP students, and paediatric language researchers screening pragmatic-discourse in children with DLD, ASD, ADHD, and TBI. Mobile-friendly, client-side, no sign-up.

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Related LSA metrics

NDW

Number of Different Words (NDW)

NDW counts unique word roots across a fixed sample length and is the most stable lexical-diversity measure for school-age children.

TTR

Type-Token Ratio (TTR)

TTR divides unique word roots by total words to index lexical diversity — quick to compute but highly sensitive to sample length.

WPM

Words Per Minute (WPM / Speech Rate)

Words per minute divides total words by speaking time and indexes speech rate — useful for dysfluency, motor speech, and cognitive-linguistic populations.

References

  1. Miller, J. F., & Iglesias, A. (2012). SALT: Systematic Analysis of Language Transcripts. SALT Software.
  2. Dollaghan, C. A., Campbell, T. F., & Tomlin, R. (1990). Video narration as a language sampling context. JSHD, 55(3), 582–590.
  3. Heilmann, J., Nockerts, A., & Miller, J. F. (2010). Language sampling: Does the length of the transcript matter? LSHSS, 41(4), 393–404.