Standardization and Calibration of the International IQ Test
Published by: International IQ Test
Last updated:
IQ scores are typically reported on a standardized scale that approximates a bell-shaped distribution in the population
(also called a "Gaussian curve"), with a mean of 100 and
a standard deviation of 15.
Objective
The goal of this analysis is to assess whether—after applying country-level weighting, internal anti-bot filtering, and
deduplication—the distribution of IQ scores aligns with a standardized IQ scale (mean ≈ 100, standard deviation ≈ 15)
across multiple years using independent samples from the
International IQ Test.
Data Analyzed
We constructed three independent, country-weighted samples intended to approximate the global population—one for each year:
2020, 2021, and 2022.
- Target sample size: 80,000 (a global population “scaled down” to 80,000 observations)
- Actual sample size per year: 66,032 test takers (82.54% of the target)
- Inclusion criteria: Selected using the country-weighting procedure described below, after internal anti-bot filtering and deduplication
Country Weighting
Each annual sample includes a per-country share of results that matches that country’s share of the world population
(reference: 2023 world population shares;
weighting follows an aggregation consistent with the United Nations classification, counting Taiwan, Hong Kong, and Macao within “China.”).
Example: In 2023, China represents approximately 18.89% of the world population. In a target sample of 80,000, that corresponds
to 15,112 results for China (18.89% of 80,000).
Global Coverage and Limitations
The available data allowed us to cover 82.54% of the target global representation in each annual sample (66,032 / 80,000).
For countries comprising the remaining 17.46%, the database did not contain enough test administrations to meet the minimum
per-country quota without substantially reducing the overall target sample size. Those countries were therefore excluded
when constructing the samples.
We do not expect this limitation to materially affect overall distributional trends, but it is a coverage constraint to keep in mind.
Results (Score Distribution)
Across the three annual samples (2020, 2021, 2022), the observed summary statistics for the final score are as follows:
- 2020: Mean = 100.86 (≈ 101), Standard deviation = 15.12 (≈ 15)
- 2021: Mean = 99.75 (≈ 100), Standard deviation = 15.15 (≈ 15)
- 2022: Mean = 99.82 (≈ 100), Standard deviation = 15.49 (≈ 15)
Overall summary (2020–2022):
- Mean ≈ 100
- Standard deviation ≈ 15
Visualization:
https://international-iq-test.com/img/iq_population_distribution_2020-2022.webp
Interpretation
These results indicate that the final IQ score is properly standardized (mean ≈ 100, standard deviation ≈ 15) after applying
country-level weighting, internal anti-bot filtering, and deduplication, and that this standardization remains consistent
across three consecutive years (2020–2022).
Transparency
- What this shows
- Statistically consistent calibration and standardization of the final IQ score produced by the International IQ Test
- Overall stability of the score distribution across multiple years (within the limits of sampling and coverage)
- What this does not replace