Statistics of Cooijmans Intelligence Test 5

Scores on Cooijmans Intelligence Test 5 as of 15 January 2023

Contents type: Verbal, numerical, spatial.   Period: 2016-present

• n: 64
• Median: 6.0
• Quartile deviation: 3.0
• Range: 29
• Maximum possible: 40
• Male median: 6.0 (n = 64)
• No females have taken this test yet.
• Resolution: 0.35

Correlation of Cooijmans Intelligence Test 5 with other mental ability tests

Weighted average of correlations: 0.590 (N = 993, weighted sum = 585.58)

Conservatively estimated minimum g loading: 0.77

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 Cooijmans Intelligence Test 5 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 = 742

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

Balanced g loading = 0.74

National medians for Cooijmans Intelligence Test 5

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 Cooijmans Intelligence Test 5

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

• r = 0.08 (n = 64)

Correlation of Cooijmans Intelligence Test 5 with personal details

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.

Reliability

• Split-half (odd-even) = 0.98
• Split-half (1, 2… 5, 6… vs. 3, 4… 7, 8…) = 0.96
• Cronbach's alpha = 0.93

Remark: In recent years, the extremely mistaken notion has arisen in incompetent dilettante circles that a very high reliability (such as reported above) be bad because it supposedly mean that "all items measure the same" and the test lack diversity. An explanation as to this grave fallacy can be found here under "Confusion with internal consistency".

Error

• Standard error = 1.8 raw score points

Scores by age

N = 64

Scores by year taken

r_{year taken × median score} = 0.02 (N = 64)

Remark: In 2020, this test was used for the Prize of the Beheaded Man, which likely explains the high median and many scores of that year.

Robustness and overall test quality

• Robustness by chronological rank = 0.65
• Robustness by month = 0.62 (r_{raw scores × months} = 0.22)
• Quality = 0.752

Correlations of sections with total score

Correlations between sections (internal consistency versus profile information)

Ideal values for correlations between sections are around .5, thus being a compromise between the test's ability to yield a "profile" and its ability to provide an indication of general intelligence. With a too high correlation (like .8 or higher) the sections measure basically the same so there is almost no profile information in them, with a too low correlation (like .2 or lower) the sections are so different that there is little point in combining them into a measure of general intelligence.

Section histograms

Prop. = proportion of candidates outscored in this section. In parentheses the proportion outscored for any possible scores higher than the present score but lower than the next-higher score in the table.

Verbal

Numerical

Spatial

Item analysis

Item statistics are not published as that would help candidates. To detect bad items, answers and comments from candidates are studied, as well as, for each problem, the correlation with total score on the remaining problems (item-rest correlation) and the proportion of candidates getting it wrong (hardness of the item). Possible bad items are revised, replaced, or removed, possibly resulting in a revised version of the test.

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