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Historical basic numeracy rates

About this data

Historical basic numeracy rates
Age heaping is observed in age data collection, where people tend to report their ages in rounded figures, often ending in 0 or 5, rather than their exact age. For example, individiauals might state their age as 30, 35, or 40 and avoid being precise with figures like 31, 36, or 39. This is believed to happen more often in populations that lack basic numeracy skills. Age heaping can therefore be used to estimate historic data on basic numeracy across different regions and timeframes. To estimate age heaping (also known as Whipple index) the authors of this dataset divide the number of people who report their ages to end in 0 or 5 by the expected real age distribution if ages were evenly distributed, meaning ages ending in 0 or 5 would appear about one-fifth of the time. They then perform a simple transformation of the Whipple index that can be interpreted as the share of individuals that correctly report their age.
Source
Baten et al. (2013) – processed by Our World in Data
Last updated
August 9, 2023
Date range
1500–1970
Unit
%

Sources and processing

This data is based on the following sources

Baten et al. – Numeracy (Total)

Age heaping refers to the tendency for age data collected in surveys or censuses to be disproportionately reported at certain "attractive" or "round" numbers. This phenomenon often manifests itself in ages being reported at numbers that end in 0 or 5.

For example, when people are asked their age, they might be more likely to report it as 30, 35, 40, etc., rather than the exact age of 31, 36, or 39.

The authors of this dataset use this "age heaping" to measure cognitive ability in quantitative reasoning, or "numeracy" and construct a database of age heaping-based estimates of basic numeracy with broad geographic and temporal coverage.

Retrieved on
August 9, 2023
Retrieved from
https://clio-infra.eu/Indicators/NumeracyTotal.html
Citation
This is the citation of the original data obtained from the source, prior to any processing or adaptation by Our World in Data. To cite data downloaded from this page, please use the suggested citation given in Reuse This Work below.
Baten, Joerg, University of Tuebingen; with the help of several coauthors, without implying any responsibility to them for potential mistakes (Valeria Prayon, Dorothee Crayen, Dácil Juif, Ralph Hippe, Christina Mumme and many others) (2013). Numeracy (Total) via Clio Infra.

Age heaping refers to the tendency for age data collected in surveys or censuses to be disproportionately reported at certain "attractive" or "round" numbers. This phenomenon often manifests itself in ages being reported at numbers that end in 0 or 5.

For example, when people are asked their age, they might be more likely to report it as 30, 35, 40, etc., rather than the exact age of 31, 36, or 39.

The authors of this dataset use this "age heaping" to measure cognitive ability in quantitative reasoning, or "numeracy" and construct a database of age heaping-based estimates of basic numeracy with broad geographic and temporal coverage.

Retrieved on
August 9, 2023
Retrieved from
https://clio-infra.eu/Indicators/NumeracyTotal.html
Citation
This is the citation of the original data obtained from the source, prior to any processing or adaptation by Our World in Data. To cite data downloaded from this page, please use the suggested citation given in Reuse This Work below.
Baten, Joerg, University of Tuebingen; with the help of several coauthors, without implying any responsibility to them for potential mistakes (Valeria Prayon, Dorothee Crayen, Dácil Juif, Ralph Hippe, Christina Mumme and many others) (2013). Numeracy (Total) via Clio Infra.

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“Data Page: Historical basic numeracy rates”. Our World in Data (2026). Data adapted from Baten et al.. Retrieved from https://archive.ourworldindata.org/20260512-000143/grapher/share-of-the-population-with-basic-numeracy-skills-by-birth-decade.html [online resource] (archived on May 12, 2026).

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Baten et al. (2013) – processed by Our World in Data

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Baten et al. (2013) – processed by Our World in Data. “Historical basic numeracy rates” [dataset]. Baten et al., “Numeracy (Total)” [original data]. Retrieved May 12, 2026 from https://archive.ourworldindata.org/20260512-000143/grapher/share-of-the-population-with-basic-numeracy-skills-by-birth-decade.html (archived on May 12, 2026).

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