Statistics of birth year

Known Years of birth as of 6 June 2022

Contents type: Personal information.   

• n: 1936
• Median: 1977.5
• Quartile deviation: 9.5
• Range: 95
• Male median: 1978.0 (n = 1619)
• Female median: 1976.0 (n = 309)
• Intersexual median: 1995.0 (n = 1)
• Resolution: 0.63

Remark: The slightly earlier median birth year of females may reflect the fact that women live longer than men on average.

Birth years of males

n = 1619

Birth years of females

n = 309

Correlation of Year of birth with other tests by I.Q. Tests for the High Range

Weighted average of correlations: -0.050 (N = 5200, weighted sum = -257.66)

Conservatively estimated minimum g loading: -0.22

Ranking in above table is based on the unrounded correlations. All available data is present in this table, no tests are left out except for those with less than 4 score pairs. All known pairs are used, including possible floor/ceiling scores or outliers.

Remark: The negative g loading means that earlier birth years do slightly better on the whole.

Correlation of Year of birth with tests by others

Weighted average of correlations: 0.004 (N = 1886, weighted sum = 7.39)

Ranking in above table is based on the unrounded correlations. All available data is present in this table, no tests are left out except for those with less than 4 score pairs. All known pairs are used, including possible floor/ceiling scores or outliers.

Please be aware that correlations with these external tests are in most cases affected (depressed, typically) by one or more of the following: (1) Little overlap with the object test because of the much lower ceilings and inherent ceiling effects of the tests used in regular psychology; (2) Candidates reporting scores selectively, for instance only the higher ones while withholding lower ones; (3) Candidates reporting, or having been reported by psychometricians, incorrect scores.

Correlation of Year of birth with other tests by I.Q. Tests for the High Range - for females

Weighted average of correlations: -0.097 (N = 277, weighted sum = -26.99)

Conservatively estimated minimum g loading among females: -0.31

Ranking in above table is based on the unrounded correlations. All available data is present in this table, no tests are left out except for those with less than 4 score pairs. All known pairs are used, including possible floor/ceiling scores or outliers.

Estimated loadings of Year of birth on particular item types

These are estimated g factor loadings, but against homogeneous tests (containing only particular item types) as opposed to non-compound heterogeneous tests. Although tending to surprise the lay person, it is not uncommon for tests to have high loadings on item types they do not actually contain themselves. Such loadings reflect the empirical fact that most tests for mental abilities measure primarily g, regardless of their contents; that the major part of test score variance is caused by g, and only a minor part by factors germane to particular item types. It is of key importance to understand that this is a fact of nature, a natural phenomenon, and not something that was built into the tests by the test constructors.

N = 4396

Compound tests have been left out of this table to avoid overlap.

Balanced g loading = -0.05

Remark: It seems that persons with earlier birth years do better on verbal tests and persons with later birth years do better on spatial tests. This matches the existing notion in psychometrics that spatial ability peaks early, and recalls the phenomenon that literary authors tend to reach their peaks beyond middle age, like in their sixties.

National medians for Year of birth

For reasons of privacy, only countries with 2 or more candidates are included in this table. Ranking is based on the medians, and then alphabetic.

Correlation with national I.Q.'s of Year of birth

Correlation of this test with national average I.Q.'s published by Lynn and Vanhanen:

• r = -0.08 (n = 1526) (significant)

Correlation of Year of birth with personal details

Remark: Earlier birth years have higher educational levels, behave better, have wider associative horizons, and are more ethical. Later birth years score higher on various indicators of deviance, are more preferring to deal with things rather than humans, are lower in empathy, more introverted, more inclined to hurt others, more desiring to punish wrongdoers, and have higher-educated mothers.

Correlation with personal details of Year of birth - within females

Correlation with personal details of Year of birth - within males

Estimated g factor loadings upward and downward of particular scores

In parentheses the number of score pairs on which that estimated g factor loading is based. The goal of this is to verify the hypothesis that g becomes less important, accounts for a smaller proportion of the variance, at higher I.Q. levels. The mere fact of restricting the range like this also depresses the g loading compared to computing it over the test's full range, so it would be normal for both values to be lower than the test's full-range g loading.

Remark: Although these are all small, it can be deduced from this table that the g loading of birth year is negative for the recent birth years and positive for the remote birth years. In other words, that the middle generations score highest. This is consistent with the known scores by age.

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