# CTS - Cohort Transfer Slope

- Artifact: PictoClarity metric reference
- Canonical HTML URL: https://pictoclarity.com/framework/metrics/cts/
- Markdown URL: https://pictoclarity.com/md/framework/metrics/cts/
- Language: en
- Category: Supporting metric

## Summary

A slope for how PictoClarity Score changes across modeled birth cohorts.

## Definition

CTS measures the rate of PCS change across modeled birth cohorts in the current evidence window.

## Formula Structure

`CTS = abs(PCS_oldest - PCS_youngest) / n`

This public formula describes structure, not private calibration.

## What It Reads

- Whether clarity decays sharply or remains stable across cohorts.
- How fast a learned convention loses transfer reliability.
- Whether a pictogram needs cohort-specific support or replacement.

## High Reading

A high CTS means clarity changes materially across cohorts.

## Low Reading

A low CTS means the modeled transfer profile is comparatively stable across cohorts.

## Limits

- CTS should be compared inside the same evaluation context.
- CTS can flatten when evidence is sparse or when cohort signals are weak.
- CTS summarizes the modeled curve; it does not explain every local variation.

## Examples

- A legacy interface metaphor can show a stronger CTS when younger cohorts lose direct object familiarity.
- A simple restroom pictogram can show a lower CTS when recognition remains stable across cohorts.

## Related Metrics

- PCS
- CBB
- NTR
- ERS

## Citation Guidance

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