Research you can check, cite and reuse
Original studies, rankings and technical reports from the IQ Metrics research team. Every number links to its source, every study publishes its method, and the data is yours to download under CC BY 4.0.
- Named primary sources
- Method with every study
- Open data, CC BY 4.0
Every study, newest first
Data studies built from public sources, reports from our own test results, explainers of published research and technical reports. Filter by type or search by topic, place or source.
Mensa by the numbers
Mensa membership by country and per person, the worldwide total its own websites disagree on, and 39 children who joined in two years of news.
Key findingSweden has the most members per person; the national counts add up to about 143,000.
The smartest states in the US, 2026
All 50 states ranked on NAEP 2024 school test scores and the share of adults with a college degree, with income, school spending, adult skills and the change since 2006 beside the ranking.
Key findingMassachusetts ranks first with an index score of 79.1; 49 of 50 states scored lower on NAEP in 2024 than in 2019.
At what age is your brain sharpest?
Peak ages for 15 thinking skills from 756,948 adults: when each skill peaks, how fast it declines, and how education and the time of day relate to scores.
Key findingOverall performance peaks at 25; math reasoning peaks latest, at 36.
How IQ Metrics Research works: methods and standards
The rules behind every study: sources and licences, the eight-step build, own-data privacy rules, uncertainty, how to check a number, independence and corrections.
Key findingSources that forbid commercial reuse are refused; no study is sponsored; own-data groups under 100 people are never published.
No study matches those filters.
Download the data behind every chart
Each dataset is the full table a study was built from, one row per place or group, with a column dictionary in the study's method section.
| Dataset | From the study | Size | Licence | Updated | Download |
|---|---|---|---|---|---|
| Mensa by the numbers 2026 (national membership)mensa-statistics-2026-iqmetrics.csv | Mensa statistics | 28 rows × 14 columns | CC BY 4.0 | Oct 2026 | Download CSV |
| Smartest States Index 2026smartest-states-2026-iqmetrics.csv | Smartest States 2026 | 50 rows × 36 columns | CC BY 4.0 | Oct 2026 | Download CSV |
| Peak Brain Age 2026 (aggregate results)peak-brain-age-2026-iqmetrics.csv | Peak brain age | 19 rows × 12 columns | CC BY 4.0 | Oct 2026 | Download CSV |
Six rules every study follows
The same standards apply to a fifty-state index and to a two-page explainer. The full method, with the licences of every source we use and refuse, is published as its own report.
Named primary sources
Every figure traces to a named publisher: a national statistics agency, an international survey such as NAEP, PISA or PIAAC, or our own aggregated test results. Each one is linked.
The method is published
Each study explains, step by step, how the numbers were combined, with the weights and formulas, so anyone can rebuild the result from the same sources.
Uncertainty is shown
Where a source reports standard errors or margins of error, we carry them through. Close rankings are shown as likely-rank ranges, not single places.
Open data, open licence
Every study's table can be downloaded as a CSV under CC BY 4.0. Reuse it in your own work with a credit and a link to the study.
Privacy by design
Reports built on our own test results use totals only. Groups with fewer than 100 people are not published, and no personal data leaves our servers.
Dated corrections
Mistakes are fixed on the study page with a dated note in its version history. Studies are refreshed when their sources release new data.
Sources we use and refuse, the eight build steps, privacy rules and corrections.
What we are working on next
Studies in preparation. Each one follows the same rules, and each one ships with its data.
Smartest Countries Index 2026
Student and adult skills across countries, combined from OECD PISA 2025, PIAAC and World Bank learning data. A skills index, not a national IQ.
- Planned
- Data
- Analysis
- Review
IQ test scores by country, 2026
Average scores on the IQ Metrics test by country, from first attempts only, for countries with at least 100 test takers.
- Planned
- Data
- Analysis
- Review
For writers, researchers and journalists
Cite IQ Metrics Research
Each study has its own citation in four styles at the foot of the page. To cite the research section as a whole:
IQ Metrics Research. (2026). IQ Metrics Research: Data studies and open data. IQ Metrics. https://iqmetrics.org/research/
IQ Metrics Research. "IQ Metrics Research: Data Studies and Open Data." IQ Metrics, 2026, iqmetrics.org/research/
IQ Metrics Research. "IQ Metrics Research: Data Studies and Open Data." IQ Metrics. Accessed 16 October 2026. https://iqmetrics.org/research/.
@misc{iqmetricsresearch, author = {{IQ Metrics Research}}, title = {IQ Metrics Research: Data Studies and Open Data}, year = {2026}, url = {https://iqmetrics.org/research/} }
Working on a story?
Everything on these pages is built to be reused with a credit and a link.
- The full data behind every chart, as a CSV
- Every chart as a print-ready PNG, and a share card with the credit built in
- Ready quotes under each study, attributable to the named analyst
- Corrections made in public, with a date
- Credit line
- "IQ Metrics Research" with a link to the study you used. On air or in print, "IQ Metrics" and the page address are enough.
- Embargoes
- None. A study is live and citable the day it is published, and stays at the same address when it is refreshed.
- Comment
- Ready quotes sit in every study's press kit. For a quote on a specific figure, or the breakdown behind any number, write to the desk.
- Reply time
- Usually within one working day. A reported error is checked the same day.
Who builds and checks the studies
Leon Falkner
Data & Research AnalystLeon owns the arithmetic on IQ Metrics: the percentile tables, the score converter and the figures in everyone else's drafts. On the research desk Leon pulls the data, builds each index and writes the method.
Profile and other work
Aarav Vardhan
Editor-in-ChiefAarav is the standing reviewer on every page that reports a score, a percentile or a research finding, and signs off each study before it is published. Aarav is also the named contact for corrections.
Profile and other workWhat changed, and when
- Version 2026.10
Methods and standards: Added: how to check a number, independence and funding, working with journalists. Source table updated for the NCPT dataset, World Bank population, organisations' own figures, the Wayback Machine and news counts.
- Version 2026.10
Mensa statistics: First release.
- Version 2026.10
Smartest States 2026: First published.
- Version 2026.10
Peak brain age: First release.
- Version 2026.10
Methods and standards: First published.
About IQ Metrics Research
What is IQ Metrics Research?
The research section of iqmetrics.org. It publishes data studies and indexes built from public sources, reports from our own aggregated test results, plain-English explainers of published research, and technical reports on how our test works.
Can I use your data and charts?
Yes. Studies and datasets are published under the Creative Commons Attribution 4.0 licence (CC BY 4.0). Credit IQ Metrics Research and link to the study page you used.
Is your research peer reviewed?
No. Each study is checked by our editor before it is published, and its method, sources and data are published so anyone can check the work. If you find an error, tell us through the contact page and we will correct it with a dated note.
Why don't you publish an IQ by country ranking?
School and adult skills surveys such as PISA and PIAAC measure skills, not IQ, and converting them into IQ points adds assumptions the data cannot support. We publish skills indexes and call them that.
How often are studies updated?
When the underlying source releases new data. Reports built on our own test results are refreshed every January at the same address, so links to them keep working.
Curious where your own score falls?
Take the IQ Metrics test and see how your own result compares.
Cite
Falkner, L. (2026). Mensa by the numbers (Version 2026.10) [Data set]. IQ Metrics Research. https://iqmetrics.org/research/mensa-statistics/
Falkner, Leon. "Mensa by the numbers." IQ Metrics Research, 16 Oct. 2026, iqmetrics.org/research/mensa-statistics/.
Falkner, Leon. "Mensa by the numbers." IQ Metrics Research. October 16, 2026. https://iqmetrics.org/research/mensa-statistics/.
@misc{iqmetrics2026mensastatistics, author = {Falkner, Leon}, title = {Mensa by the numbers}, institution = {IQ Metrics}, year = {2026}, version = {2026.10}, url = {https://iqmetrics.org/research/mensa-statistics/} }
Source: Leon Falkner, "Mensa by the numbers." IQ Metrics Research, version 2026.10, https://iqmetrics.org/research/mensa-statistics/
Falkner, L. (2026). The smartest states in the US, 2026 (Version 2026.10) [Data set]. IQ Metrics Research. https://iqmetrics.org/research/smartest-states-in-america/
Falkner, Leon. "The smartest states in the US, 2026." IQ Metrics Research, 15 Oct. 2026, iqmetrics.org/research/smartest-states-in-america/.
Falkner, Leon. "The smartest states in the US, 2026." IQ Metrics Research. October 15, 2026. https://iqmetrics.org/research/smartest-states-in-america/.
@misc{iqmetrics2026smarteststatesinamerica, author = {Falkner, Leon}, title = {The smartest states in the US, 2026}, institution = {IQ Metrics}, year = {2026}, version = {2026.10}, url = {https://iqmetrics.org/research/smartest-states-in-america/} }
Source: Leon Falkner, "The smartest states in the US, 2026." IQ Metrics Research, version 2026.10, https://iqmetrics.org/research/smartest-states-in-america/
Falkner, L. (2026). At what age is your brain sharpest? (Version 2026.10) [Data set]. IQ Metrics Research. https://iqmetrics.org/research/peak-brain-age/
Falkner, Leon. "At what age is your brain sharpest?" IQ Metrics Research, 15 Oct. 2026, iqmetrics.org/research/peak-brain-age/.
Falkner, Leon. "At what age is your brain sharpest?" IQ Metrics Research. October 15, 2026. https://iqmetrics.org/research/peak-brain-age/.
@misc{iqmetrics2026peakbrainage, author = {Falkner, Leon}, title = {At what age is your brain sharpest?}, institution = {IQ Metrics}, year = {2026}, version = {2026.10}, url = {https://iqmetrics.org/research/peak-brain-age/} }
Source: Leon Falkner, "At what age is your brain sharpest?" IQ Metrics Research, version 2026.10, https://iqmetrics.org/research/peak-brain-age/
Falkner, L. (2026). How IQ Metrics Research works: methods and standards (Version 2026.10). IQ Metrics Research. https://iqmetrics.org/research/methods/
Falkner, Leon. "How IQ Metrics Research works: methods and standards." IQ Metrics Research, 15 Oct. 2026, iqmetrics.org/research/methods/.
Falkner, Leon. "How IQ Metrics Research works: methods and standards." IQ Metrics Research. October 15, 2026. https://iqmetrics.org/research/methods/.
@techreport{iqmetrics2026methods, author = {Falkner, Leon}, title = {How IQ Metrics Research works: methods and standards}, institution = {IQ Metrics}, year = {2026}, version = {2026.10}, url = {https://iqmetrics.org/research/methods/} }
Source: Leon Falkner, "How IQ Metrics Research works: methods and standards." IQ Metrics Research, version 2026.10, https://iqmetrics.org/research/methods/