Statistics of Isis Test

Scores on Isis Test as of 23 February 2023

Contents type: Verbal, numerical.   Period: 2001-present

• n: 100
• Mean: 0.18
• Standard deviation: 0.46
• Range: 2.0
• Maximum possible: 5
• Male mean: 0.20 (n = 92)
• Female mean: 0.00 (n = 7)
• Proportion of males among candidates: 0.920
• Hardness: 0.96
• Resolution: 0.00

Correlation of Isis Test with other mental ability tests

Weighted average of correlations: 0.368 (N = 1159)

Estimated g factor loading: 0.61

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.

The correlations with other tests are uncommonly low as a result of the limited variance of raw scores on this test.

Estimated loadings of Isis Test 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 = 872

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

Balanced g loading = 0.53

National means for Isis Test

For reasons of privacy, only countries with 3 or more candidates are included in this table. Ranking is based on the unrounded means, and then alphabetic.

Correlation with national I.Q.'s of Isis Test

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

• r = 0.12 (n = 93)

Correlation of Isis Test with personal details

Reliability and error

Due to the small number of items and limited variance in scores and item scores, it is not possible to compute reliability and error meaningfully for this test from its internal statistics. What can be said is that a test's reliability is necessarily higher than its g loading because reliability forms the upper limit of a test's possible correlations with any other variables.

Scores by age

N = 96

Scores by year taken

r_{year taken × mean score} = 0.07 (N = 100)

Robustness and overall test quality

• Robustness by month = 0.69 (r_{raw scores × months} = 0.04)
• Quality = 0.596

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.

[More statistical reports]