Source: https://guthlabs.ai/docs/instruments/adult-growth-chart-height-percentile/implementation/

instrument implementation / implementation-contract

# Adult Growth Chart / Height Percentile implementation

A source-bound implementation contract for Adult Growth Chart / Height Percentile; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-045

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero-SD reference causes an undefined 0/0 z-score, and an unspecified height unit can change the reported percentile from effectively 0% to approximately 60.15%. A zero height also exposes the need for physical-range validation.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "height_cm": 162,
    "sex": "female",
    "population_reference": "US adults, female, rounded test fixture",
    "mean_height_cm": 162,
    "sd_height_cm": 6.5,
    "z_cdf_method": "standard normal CDF table"
  },
  "expected_outputs": {
    "z_score": 0,
    "percentile": 50
  },
  "reference_data": {
    "mean_height_cm": 162,
    "sd_height_cm": 6.5,
    "source_convention": "CDC/NHANES-style rounded adult-height reference fixture; exact release and age band must be specified",
    "standard_normal_cdf": {
      "z": 0,
      "Phi_z": 0.5,
      "source_convention": "widely tabulated standard normal CDF value"
    }
  },
  "working": "1. z = (162.0 - 162.0) / 6.5 = 0.0 / 6.5 = 0.0000. 2. From the standard normal table, Phi(0.00) = 0.5000. 3. Percentile = 100 * 0.5000 = 50.00."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/adult-growth-chart-height-percentile/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/adult-growth-chart-height-percentile/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/adult-growth-chart-height-percentile/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-tranche7/tranche7-results.json`