Whipple's index (or index of concentration), invented by American demographer

George Chandler Whipple George Chandler Whipple (March 2, 1866 – November 27, 1924) was an American civil engineer and an expert in the field of sanitary microbiology. His career extended from 1889 to 1924 and he is best known as a co-founder of the Harvard School of ...

(1866–1924), is a method to measure the tendency for individuals to inaccurately report their actual age or date of birth. Respondents to a

census A census (from Latin ''censere'', 'to assess') is the procedure of systematically acquiring, recording, and calculating population information about the members of a given Statistical population, population, usually displayed in the form of stati ...

or other survey sometimes report their age or date of birth as a

round Round or rounds may refer to: Mathematics and science * Having no sharp corners, as an ellipse, circle, or sphere * Rounding, reducing the number of significant figures in a number * Round number, ending with one or more zeroes * Round (crypt ...

number (typically ending in 0 and 5), or to be more culturally favorable, for example, so that they appear younger or to have been born on a date considered luckier than their actual date of birth. The process of reporting a rounded or “lucky” age is known as age-heaping.

Calculation

The index score is obtained by summing the number of persons in the age range 23 and 62 inclusive, who report ages ending in 0 and 5, dividing that sum by the total population between ages 23 and 62 years inclusive, and multiplying the result by 5. Restated as a percentage, index scores range between 100 (no preference for ages ending in 0 and 5) and 500 (all people reporting ages ending in 0 and 5). The UN recommends a standard for measuring the age heaping using Whipple's Index as follows:

Applicability

Although Whipple's index has been widely applied to test for age heaping, it assumes that the heaping is most likely to occur in 5 and 10 year intervals or some other fixed interval based on digit preference or rounding. While other measures of age heaping, such as Myers' Blended Index, can be applied to find preferences for any terminal digit, the patterns of heaping may be complex. For example, it has been shown that among

Han Chinese The Han Chinese, alternatively the Han people, are an East Asian people, East Asian ethnic group native to Greater China. With a global population of over 1.4 billion, the Han Chinese are the list of contemporary ethnic groups, world's la ...

, age heaping occurs on a 12-year cycle, consistent with preferred animal years of the

Chinese calendar The traditional Chinese calendar, dating back to the Han dynasty, is a lunisolar calendar that blends solar, lunar, and other cycles for social and agricultural purposes. While modern China primarily uses the Gregorian calendar for officia ...

. Whether this heaping represents actual fertility behavior (e.g., bearing children in favorable animal years) or selective memory or reporting of year of birth has not been determined. Although the heaping is not severe among Han, and it does not seem to be associated with age exaggeration, it is systematic and is higher among illiterate populations. On the other hand, among Turkic Muslim populations in China (

Uyghurs The Uyghurs,. alternatively spelled Uighurs, Uygurs or Uigurs, are a Turkic peoples, Turkic ethnic group originating from and culturally affiliated with the general region of Central Asia and East Asia. The Uyghurs are recognized as the ti ...

and

Kazakhs The Kazakhs (Kazakh language, Kazakh: , , , ) are a Turkic peoples, Turkic ethnic group native to Central Asia and Eastern Europe. They share a common Culture of Kazakhstan, culture, Kazakh language, language and History of Kazakhstan, history ...

Xinjiang Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...

Province) there is severe heaping at ages ending in 0 and 5; it is much higher among illiterate populations and appears to be correlated with age exaggeration. These traditionally Muslim nationalities do not use the Chinese calendar. This finding suggests that use of Whipple's Index or other measures of age heaping that focus on specific digits or on decimal intervals of the age spikes may not be appropriate for all populations. In the case of China's 1990 census reported above, among Han heaping was found at ages 38, 50, 62, 74, and so on — ages that corresponded with being born in the Year of the Dragon. But among Turkic Muslims, heaping was found at ages 35, 40, 45, 50, 55, 60, and so on and increased in magnitude with age.

ABCC Index

ABCC Index is another age heaping index that is used in a research and is based on the Whipple's Index. This method was developed by A’Hearn, Baten, and Crayen. Who examined a close relationship between age heaping and a number of

human capital Human capital or human assets is a concept used by economists to designate personal attributes considered useful in the production process. It encompasses employee knowledge, skills, know-how, good health, and education. Human capital has a subs ...

indicators from the U.S. census sample namely, the race, gender, high and low educational status. Results proved a statistically significant relationship. Further, the same method was conducted on the data from 17 different European countries starting from the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

up until 19th century. The outcome has also depicted a

positive correlation In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statisti ...

between age heaping and

literacy Literacy is the ability to read and write, while illiteracy refers to an inability to read and write. Some researchers suggest that the study of "literacy" as a concept can be divided into two periods: the period before 1950, when literacy was ...

. Moreover, another study that took into consideration

Latin America Latin America is the cultural region of the Americas where Romance languages are predominantly spoken, primarily Spanish language, Spanish and Portuguese language, Portuguese. Latin America is defined according to cultural identity, not geogr ...

from the 17th to 20th century also illustrated the higher tendency to age heaping among illiterate population.

Data Selection

When applying ABCC index it is important to check the quality of the

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

and examine the institutional framework as well as the data selection process. One of the major rules is to consider only people above 23 and below 62, in order to prevent distortions effects. The justification is that the age

awareness In philosophy and psychology, awareness is the perception or knowledge of something. The concept is often synonymous with consciousness. However, one can be aware of something without being explicitly conscious of it, such as in the case of bli ...

increases when the minimal age requirements applies (e.g. marriage registration,

military conscript Conscription, also known as the draft in the United States and Israel, is the practice in which the compulsory enlistment in a national service, mainly a military service, is enforced by law. Conscription dates back to antiquity and it contin ...

voting Voting is the process of choosing officials or policies by casting a ballot, a document used by people to formally express their preferences. Republics and representative democracies are governments where the population chooses representative ...

) whereas, older people often tend to overstate their age. Moreover, it is important to note that there are different forms of age heaping, e.g. to two or to twelve. Heaping to two is more common among adults, teenagers and children.

Application

The method is often used to explore inequality of

numeracy Numeracy is the ability to understand, reason with, and apply simple numerical concepts; it is the numerical counterpart of literacy. The charity National Numeracy states: "Numeracy means understanding how mathematics is used in the real world ...

for certain populations or regions. ABCC index helps to measure differences in

for further analysis. For instance, to

evaluate In common usage, evaluation is a systematic determination and assessment of a subject's merit, worth and significance, using criteria governed by a set of standards. It can assist an organization, program, design, project or any other intervention ...

the gap between numeracy levels of the upper and the lower segments of a sample population, taken from different countries (e.g. 26 regions of France, 25 states of the USA). This inequality of human capital might in turn exerts in further studies a negative or positive relationship on subsequent economic development of selected countries.

References

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External links

Age Validation of Han Chinese Centenarians (an example of Whipple's Index misapplied)
Concentration indicators Population Sampling (statistics)