Source: https://guthlabs.ai/docs/instruments/waist-to-hip-waist-to-height-ratio/mechanism/

instrument mechanism / verified-clean

# Waist-to-Hip / Waist-to-Height Ratio mechanism

The inspectable method record for Waist-to-Hip / Waist-to-Height Ratio, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The arithmetic formulas pass standard dimensional checks, but the instrument is not fully specified because its required risk-band output cannot be determined from the provided data. Verdict is NEEDS_REVIEW until exact thresholds, band labels, demographic applicability, and measurement protocol are defined.

- WHR=waist/hip and WHtR=waist/height are standard dimensionless ratio formulas when all measurements use the same unit.

- The risk-band output is underspecified: no threshold table, threshold values, band names, or mapping rules are provided.

- The claimed WHO risk threshold bands are ambiguous because applicable thresholds may depend on sex, age, population, measurement protocol, and whether the indicator is WHR or WHtR.

## Units and conventions

- Waist, hip, and height must be measured in the same unit before division; centimeters, meters, or inches are each acceptable if used consistently.

- The ratios are dimensionless, so converting every input by the same factor does not change the result.

- Waist and hip are assumed to be circumference measurements taken using a defined anthropometric protocol; the measurement sites are not specified.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "waist": 80,
    "hip": 100,
    "height": 170,
    "unit": "cm"
  },
  "expected_outputs": {
    "WHR": 0.8,
    "WHtR": 0.4705882353,
    "risk_band_label": null
  },
  "working": "WHR = waist / hip = 80 / 100 = 0.8. WHtR = waist / height = 80 / 170 = 8 / 17 = 0.4705882353. Risk band = undetermined because no threshold table or mapping is supplied."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification exposes undefined results when hip or height is zero, does not define the risk-band threshold table or branch conventions, and leaves unit normalization unspecified; mixed units can therefore produce a numerically valid but physically nonsensical WHtR.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/waist-to-hip-waist-to-height-ratio/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/waist-to-hip-waist-to-height-ratio/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/waist-to-hip-waist-to-height-ratio/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche3/tranche3-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`