Pediatric Growth Percentile Lookup implementation

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

t7-035

Effect

Computation or source lookup only

Input and validation requirements

The specification does not define age units or table validity boundaries, does not provide the required CDC/WHO LMS tables, and gives no special handling for L=0 or invalid powers such as 0 raised to a negative L. A literal implementation can therefore return undefined results or cannot perform the lookup at all.

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": {
    "age_months": 24,
    "sex": "male",
    "measurement_type": "recumbent_length_cm",
    "value": 87.1
  },
  "expected_outputs": {
    "z_score": 0,
    "percentile": 50,
    "growth_chart_position": "50th percentile (median)"
  },
  "reference_data": {
    "source_convention": "WHO Child Growth Standards 2006, boys length-for-age LMS row at 24 months",
    "L": 1,
    "M_cm": 87.1,
    "S": 0.039,
    "normal_CDF": {
      "Phi(0)": 0.5,
      "source_convention": "NIST/standard normal distribution table"
    }
  },
  "working": "L=1, so Z=((X/M)-1)/S. X/M=87.1/87.1=1.000000. Z=(1.000000-1)/0.039=0.000000. percentile=100*Phi(0)=100*0.5=50.0%. This is exactly the tabulated median and the famous 50th-percentile entry."
}

Other records

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