Source: https://guthlabs.ai/docs/instruments/mid-parental-height-predictor/

instrument / verified-clean

# Mid-Parental Height Predictor

The current ledger marks this instrument verified clean within the source-bound verification corpus.

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

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/mid-parental-height-predictor/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/mid-parental-height-predictor/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/mid-parental-height-predictor/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/mid-parental-height-predictor/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Biology, Medicine & Pharmacology (educational estimates only — every panel labeled not-medical-advice)

**Tranche**: tranche-4

**Evidence ID**: t4-230

**Ledger rows**: 1

No ledger note is attached.

## Review findings

No division-by-zero hazard exists. The arithmetic formulas pass under the stated centimeter assumptions, but the specification needs explicit unit handling, accepted sex-input semantics, validation constraints, rounding rules, and provenance/interpretation for the ±8.5 cm range.

### Formula and scope findings

- The mid-parental formulas are standard when parental heights and constants use the same units: boys = (father + mother + 13 cm) / 2 and girls = (father + mother - 13 cm) / 2.

- The ±8.5 cm spread is a commonly used population estimate, but it is not universal; the source, population, and whether it represents a prediction interval or a clinical target range are unspecified.

### Unit assumptions

- The parental heights must be supplied in centimeters for the stated +13, −13, and ±8.5 values to be dimensionally correct.

- If heights are supplied in inches, they must be converted first: inches × 2.54 = centimeters; alternatively, the sex adjustment must be converted to 5.118 inches and the spread to approximately 3.346 inches.

- The output range is assumed to be [predicted height − 8.5 cm, predicted height + 8.5 cm].

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The plain arithmetic formulas produce a numeric result for the exactly-zero parental-height boundary instead of inherently rejecting a physically invalid input, and extreme finite JavaScript inputs overflow to Infinity. Unspecified height units also permit materially divergent interpretations.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "father_height_cm": 180,
    "mother_height_cm": 165,
    "child_sex": "boy"
  },
  "expected_outputs": {
    "predicted_height_cm": 179,
    "range_cm": {
      "lower": 170.5,
      "upper": 187.5
    }
  },
  "working": "Sum parental heights: 180 + 165 = 345 cm. Add the boy adjustment: 345 + 13 = 358 cm. Divide by 2: 358 / 2 = 179 cm. Range: 179 − 8.5 = 170.5 cm; 179 + 8.5 = 187.5 cm."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`