School-age syntax metrics
Subordination Index and C-Units
Subordination Index, often shortened to SI, is a sentence-complexity metric for language samples. ConductSpeech calculates SI by dividing total clauses by total communication units, or C-units.
For school-age samples, this helps clinicians see whether a student is using simple utterances, coordinated clauses, or more mature subordinate structures during real communication tasks.
Sample result
Subordination Index and C-Units
Sample
I think we should change lunch because it helps kids focus.
C-units
1 communication unit
Clauses
Multiple main and subordinate clauses
Counts
C-units and clauses
Metric
SI = clauses / C-units
Context
School-age syntax
Report
Included in clinical summary
Counts
C-units and clauses
Metric
SI = clauses / C-units
Context
School-age syntax
Report
Included in clinical summary
How it fits into a speech workflow
1
Collect
Start from a recording, transcript, or saved session.
2
Review
Check speaker turns and make clinical edits before relying on results.
3
Measure
See the language measures and notes that matter for this feature.
4
Use
Bring the output into reports, progress review, or research exports.
What is a C-unit?
A C-unit, or communication unit, is an independent clause with its modifiers and any attached subordinate clauses. C-units are useful for school-age language samples because they support analysis of longer and more complex utterances than early-childhood MLU alone.
What is Subordination Index?
Subordination Index is total clauses divided by total C-units. A value close to 1.0 means most C-units contain one clause. Higher values show more embedded or subordinate clauses, which can indicate more complex syntax when interpreted with the task and sample quality.
Where it appears
ConductSpeech shows SI, total C-units, total clauses, and segmentation status in the analysis dashboard. The same values are passed into clinical report generation so the report can describe syntax using the same metrics the clinician reviewed.
What users see
Worked example
A compact result view turns the feature into reviewable language, not a technical readout.
Sample
I think we should change lunch because it helps kids focus.
C-units
1 communication unit
Clauses
Multiple main and subordinate clauses
Clinical use
Supports discussion of sentence complexity
Clinical interpretation notes
- Automated clause counts should be reviewed when the transcript is unusually fragmented, dialect-rich, or syntactically ambiguous.
- SI should be interpreted with task type, sample size, and clinical judgment.
Related pages
Grade-Stratified Language Sample Norms
Compare school-age language samples by grade, age, and task type with source-aware norm explanations.
Clinical Language Sample Reports
Generate IEP-ready language sample reports with MLU, PGU, SI, C-units, maze summaries, norms, and fluency context.
SALT-Compatible Language Sample Analysis
AI language sample analysis with SALT-style coding, C-units, SI, mazes, grade norms, reliability, and clinical reports.
SALT-compatible analysis methodology
Read how ConductSpeech documents conventions, validation, and limitations.
Ready to try it
Start with a real language sample.
Create an account, upload or review a sample, and see how this feature appears inside the ConductSpeech workflow.