Question 1

What is clausal density?

Accepted Answer

Clausal density (CD) is the ratio of total clauses to total utterances (or T-units) in a language sample. Each main clause counts as one; each subordinate clause embedded inside it adds one more. CD captures syntactic complexity in a way that mean length of utterance (MLU) cannot — a child can produce long utterances by stringing together coordinated phrases, but only embedded subordinate clauses raise CD.

Question 2

Who introduced the measure and why?

Accepted Answer

Loban (1976) introduced clausal density in his 13-year longitudinal study of children's language. He showed that CD discriminates typically developing children from those with language delay better than MLU once children move past the early preschool years. Nippold (2009) extended the measure into adolescence and showed it continues to rise through age 17.

Question 3

How does the calculator detect subordinate clauses?

Accepted Answer

It uses a heuristic over a fixed list of subordinators (because, when, while, that, who, which, where, although, since, before, after, until, …). Each subordinator token after the first token of an utterance adds one subordinate clause. The first token is treated as the main-clause start, so a sentence-initial "Because I said so" still counts as a single clause.

Question 4

How accurate is the heuristic?

Accepted Answer

It is good enough for clinical screening but not for forensic-grade transcription. The heuristic will under-count zero-relatives ("the boy I saw" — there is no relativiser to detect) and may over-count subordinators that appear inside fixed phrases ("so" as a discourse marker, "as" as a comparator). Always review the per-utterance breakdown the calculator produces, and adjust counts manually before reporting in an evaluation.

Question 5

What are the developmental reference bands?

Accepted Answer

Loban (1976) and Nippold (2009) report typical CD values in roughly four bands: < 1.10 below age 5, 1.10-1.30 ages 5-8, 1.30-1.50 ages 8-12, $\geq$ 1.50 ages 12+. These are rough guides — they are not diagnostic cut-offs and they vary across sampling contexts (narrative vs. conversation). Always interpret CD against the same context the norms were collected in.

Question 6

Should I use clausal density instead of MLU?

Accepted Answer

No — use both. MLU captures utterance length and is most informative in early childhood (ages 2-5). Clausal density captures embedding and is most informative once children start producing complex syntax (age 5+). For school-age children, report both: MLU describes the surface, CD describes the depth.

Question 7

Is my data private?

Accepted Answer

Yes. The calculator runs entirely in your browser. The transcript you paste never leaves your device, and nothing is saved on our servers. Close the tab and the sample is gone.

Clausal Density Calculator

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What Is Clausal Density?

How This Calculator Works

Developmental Reference Bands

Frequently Asked Questions

Next Steps

MLU Calculator — compute MLU-morphemes from the same transcript

Lexical Diversity Calculator — TTR + NDW from the same transcript

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