The first part of this piece made the case that the 2015 Veale et al. meta-analysis is the most rigorous data set available on penile size. That remains true. Rigorous, however, is not the same as complete. And "most cited" is not the same as "universally applicable."

If you read that 5.17-inch figure and accepted it as your personal benchmark, you need to slow down. There are serious, documented methodological problems with that number that the media coverage — and, frankly, even some academic citations of the paper — have glossed over. Once you understand those problems, the "global average" looks considerably less global than advertised.

What the Study Actually Pulled Together: 20 Studies, One Number

The Veale et al. paper is described as a meta-analysis of 20 studies. That framing implies a comprehensive sweep of global data. When you look at which studies were actually pooled, a different picture emerges.

Among the contributing studies identifiable from the paper's references and screening methodology, the geographic and ethnic concentration is striking. Heavily represented populations include Caucasian British men, Italian men, Turkish men, Egyptian men, and Jordanian men. One study examined Nigerian adults. One examined Indian men. One looked at a sample from Tanzania, specifically recruited for the purpose of sizing medical circumcision devices. There is a prostate cancer surgery follow-up study from the United States in which participants were not described by ethnicity.

Conspicuously absent or severely underrepresented: Chinese men, Japanese men, Korean men, men from Southeast Asia, men from Latin America, men of Sub-Saharan African descent beyond a single 1985 Nigerian study of 320 men, Indigenous populations from any continent, and men from the Pacific Islands. The world's two most populous nations — China and India — contributed at most one study each, with India's contribution measuring a relatively small sample.

The Elephant in the Room: Ethnic Variation Is Real and Documented

The Veale et al. paper did not attempt to stratify its findings by ethnicity. That was a deliberate methodological choice, and the authors acknowledged it — noting that their goal was to establish a generalized clinical nomogram, not a breakdown by population group. The problem is how the results have been used since publication: a single figure, cited in isolation, handed to all men everywhere as a universal benchmark.

The research that has emerged since 2015 makes clear that this was always a limitation worth taking seriously. A 2025 meta-analysis published in Andrology established specific normative data for Chinese men, explicitly noting the gap Veale et al. had left. A 2024 study on WHO regional data found statistically significant variation in penile measurements across geographic regions. A broader 2023 meta-analysis published in the World Journal of Men's Health, drawing on 75 studies and 55,761 men, found that all measurements showed variation by geographic region.

These are not fringe findings or internet myths. They are peer-reviewed acknowledgments of what any honest reading of the original Veale data should have prompted researchers to ask from day one: whose data is this, really?

Measurement Inconsistency: Did All 20 Studies Follow the Same Protocol?

The Veale et al. methodology required that participating studies used clinician measurement. What it could not fully standardize was how those measurements were taken across 20 different research teams, in different countries, across publications spanning from 1985 to 2012.

This matters more than it sounds. Consider just a few of the documented variables:

Erection method: Some contributing studies achieved erect measurements through pharmacological injection of a vasoactive agent directly into the penile tissue. Others used visual or manual self-stimulation in a private room. Others still used a combination. The method of erection can produce meaningfully different degrees of tumescence — a chemically-induced erection and a naturally-occurring one are not physiologically identical in every man, particularly in older subjects or those with any vascular variation.

Measurement position: Some studies measured men in a standing position. Others measured subjects lying down. Body position affects the angle and apparent length of the erect penis relative to the measuring instrument, particularly in bone-pressed measurements where the ruler meets the pubic bone at a slightly different angle.

Room temperature: Several studies documented ambient room temperature as a variable affecting flaccid measurements. This is well-established in clinical research — cold environments reduce flaccid dimensions. While less critical for erect measurement, it introduces noise into flaccid data that carries forward into stretched-length correlations.

Who held the ruler: Even among clinician-measured studies, there is variation in the number of examiners involved, whether measurements were repeated for inter-rater reliability, and whether a rigid ruler or flexible tape was used for length.

A 2025 WHO regional meta-analysis flagged this directly: while some of its constituent studies reported standardized methods, others used non-standardized or subjective techniques, potentially affecting the reliability and comparability of the data. The same criticism applies to the source studies feeding Veale et al.

The English-Language Filter: A Built-In Geographic Bias

Here is a limitation the paper states explicitly but that rarely gets quoted in media coverage: the Veale et al. team searched only English-language literature. Their screening process evaluated 16,678 publications — but only those published in English.

Consider what this excludes. The Chinese medical literature is extensive and largely published in Mandarin. Spanish-language urological research covers populations across Latin America and Spain. Portuguese-language research covers Brazil — the world's sixth most populous nation. Japanese and Korean urology journals have published penile measurement data not captured in English databases.

The 2025 Andrology meta-analysis on Chinese men addressed this gap directly, searching Chinese-language databases including China Biology Medicine disk, China National Knowledge Infrastructure, and others — databases that Veale et al. never touched. When that research team compared their Chinese-specific findings to the Veale global figures, the differences were statistically significant.

An English-language filter on a study claiming to establish global averages is not a minor technical footnote. It is a structural boundary that defines whose data gets counted and whose doesn't.

Publication Bias: The Studies That Never Showed Up

Meta-analyses are only as representative as the studies they can find. And the studies researchers can find are not a random sample of all studies ever conducted — they are a sample skewed toward studies that found something interesting enough to publish.

In research, this is called publication bias, and it is a recognized problem across all fields of medicine. Studies that report averages close to previously assumed figures, or that find no significant variation, are less likely to be written up, submitted, and accepted than studies that report novel findings. In the context of penile size research, this means studies reporting averages at the higher end of the distribution may be more visible in the published literature than studies reporting lower averages.

A 2025 WHO regional meta-analysis acknowledged this problem explicitly, noting that studies with significant or favorable results are more likely to be published and that this publication bias could lead to an overestimation of average sizes reported in the literature. If that overestimation is baked into the source studies feeding Veale et al., then the pooled 5.17-inch figure may itself sit above the true population mean — not below it.

The Age Distribution Problem

The Veale et al. paper does not report a consistent age range across all 20 contributing studies. Some studies drew from young men — university students, military recruits, men attending fertility clinics. Others drew from older outpatient populations, including men attending urology clinics for unrelated conditions. One contributing US study specifically measured men undergoing radical prostatectomy for prostate cancer, a population with a mean age that skews significantly older than the general male population.

Why does this matter? Because penile dimensions do change with age. Research has documented modest reductions in both length and girth in older men, linked to changes in vascular health, testosterone levels, and connective tissue elasticity. A study weighted toward younger men will produce a different mean than one weighted toward men over 60 — and Veale et al. pooled both without adjusting for age distribution differences across the contributing studies.

What Other Research Has Found When They Looked More Carefully

The heterogeneity problem — the degree to which pooled studies actually differ from one another — is not speculative. It shows up in the numbers when you look.

The 2023 Belladelli et al. meta-analysis, published in the World Journal of Men's Health, aggregated 75 studies covering 55,761 men and found a pooled mean erect length of 13.93 cm (5.49 inches) — meaningfully higher than Veale's 13.12 cm (5.17 inches). It also found significant heterogeneity between studies, with an I² statistic of 98.9% — a value indicating that the variation between individual study results was enormous. An I² of 98.9% effectively means the individual studies were not measuring the same underlying population. Pooling them into a single mean produces a number that may not accurately describe any specific group of men.

That same 2023 analysis found that all measurements showed variation by geographic region. The Middle Eastern nomogram study published the same year as Veale et al. — in which one of Veale's own co-authors participated — found a mean bone-pressed erect length of 14.34 cm (5.65 inches) in a Saudi Arabian cohort, notably higher than the pooled Veale figure. The Indian study that contributed to Veale's pool has reported figures lower than the pooled mean. The Chinese meta-analysis from 2025 found averages that differed significantly from the Veale global figure.

In short: every time researchers have looked at a specific population group in isolation, rather than pooling all groups together, they have found that the group's actual average diverges from Veale's 5.17 inches. Sometimes above. Sometimes below. The pooled number smooths those differences out — and in doing so, it describes a statistical composite that may not accurately represent the typical measurement of any real ethnic group of men.

The Heterogeneity Score That Should Have Made Headlines

In statistics, when researchers combine multiple studies in a meta-analysis, they calculate a measure called I² (I-squared) to quantify how much of the variation in results is due to actual differences between the studies rather than random chance. An I² of 0% means all studies are measuring the same thing. An I² of 100% means every study is measuring something meaningfully different from the others.

The 2023 Belladelli meta-analysis, which incorporated the Veale studies as part of a larger pool, reported an I² of 98.9% for erect length. That number should have been front-page news in every journal that has ever cited Veale's 5.17 inches as a universal benchmark. An I² approaching 99% is not a mild caution. It is a direct statistical statement that the individual studies being pooled are so different from one another that a single pooled mean is of limited descriptive value for any specific population.

Put it another way: if you average the height of NBA centers with the height of jockeys and produce a mean of 5'11", that number is technically accurate as an average of those two groups. It does not tell an NBA center how tall he is, and it does not tell a jockey how tall he is. The I² for that calculation would be enormous — because the two populations are genuinely different. The same logic applies here.

So Is the Veale Study Worthless?

No. That is not the argument. The Veale et al. meta-analysis remains the most methodologically careful attempt to synthesize clinician-measured penile size data that existed in the English-language literature at the time of its publication. The insistence on clinician measurement was a genuine and important advance over self-reported surveys.

But the way the study has been received and applied — as a universal number applicable to all men, a global "normal" benchmark that every individual male should measure himself against — goes beyond what the data actually supports. The study's own authors acknowledged that they did not stratify by ethnicity and that their findings were limited to the populations contributing to the pooled sample. That acknowledgment has not followed the 5.17-inch figure into popular coverage, medical waiting rooms, or men's health websites.

What a man from Lagos, a man from Shanghai, a man from São Paulo, and a man from Stockholm each compares himself to should not be the same number. The science, looked at honestly, does not support that equivalence. The appropriate clinical response is not to discard the Veale figure — it is to treat it as one data point among several, and to demand more population-specific research rather than accepting a single pooled mean as a universal verdict.

The Verdict: A Useful Benchmark With a Significant Asterisk

The 5.17-inch figure is not a lie. It is an honest average of the data that was available, collected using a methodology that was more rigorous than most of what came before it. Within those boundaries, it is legitimate.

But those boundaries are tight. The study drew from a geographically concentrated sample, searched only English-language literature, pooled ethnically distinct populations without stratification, and could not fully standardize measurement protocols across 20 different research teams operating in different countries across different decades. The studies it pooled show near-maximal heterogeneity when examined statistically. Every population-specific study that has followed has found its own group's average diverges from the pooled mean.

A man deserves to know what the data actually shows — including what the data cannot yet show. Any single universal number applied to all men on earth should invite skepticism. The honest answer, based on the available evidence, is that global averages in this area are still incomplete, still evolving, and still weighted toward populations that represent a fraction of the world's men. That is not a reassuring conclusion. It is an accurate one.