Draft:Penis size index

The Penis Size Index (PSI) is a proposed biometric parameter that quantifies male genital dimensions through geometric modeling. First conceptualized in Chinese andrological research, the index derives from volumetric calculations of penile morphology.

Mathematical Basis

The PSI models the penis as a conical frustum (truncated cone), with its formula derived from the solid's volume equation:

$\text{PSI}=h\times (C^2+c^2+C\times c)$

where:

• h = Length from glans to base (decimeters)
• C = Base circumference (decimeters)
• c = Glans circumference (decimeters)

This formulation omits the constant coefficient (π/12) from the geometric volume formula $V=\frac{\pi h}{12}(C^2+c^2+Cc)$ to create a unitless index.

Classification Standards

Based on epidemiological data from 27,000 adult males, the classification system is defined as:

PSI Range	Clinical Category
0–1	Small
1–3	Below average
3–6	Normal range
6–8	Above average
>8	Large

Historical Development

The index emerged from volumetric comparisons in Wang's 2020 morphological study, which identified strong correlations (r = 0.82) between frustum-model calculations and MRI-measured penile volumes.

Research Applications

Preliminary applications in Chinese urology include:

• Preoperative planning for hypospadias repair
• Standardization of erectile dysfunction assessments

Criticism

Controversies persist regarding:

• Ethnic measurement biases in source data
• Non-linear correlation with physiological function
• Limited adoption beyond Chinese medical literature

See Also

• Body mass index
• Anthropometry
• Frustum
• Human variability