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About Age and Sex

The Significance of Age and Sex Data

In general, the U.S. population continues to grow older with a median age over 40 years old in many states. At the same time, increases in the number of men at older ages are apparent. Understanding a population’s age composition, usually examined by sex, yields insights into changing population conditions and can highlight future social and economic trends. See the information on which survey and programs collect these data.

Purpose of the two-part question, “What is your age and what is your date of birth?”

The purpose of this two-part question frequently used in Census Bureau questionnaires is to ensure accuracy of age data and to minimize non-response rates. Because age is a critical element in determining federal funding, it is imperative to have high quality age data. Age is also a basic demographic characteristic that is crossed by social characteristics, such as marital status and education, and economic characteristics, such as labor force participation and poverty, in many data products. Especially because of the multiple uses of age data and their visibility, it is important that they be of high quality. Asking for both date of birth in month, day, and year format, along with age, helps to ensure that quality.

Distinction between the concepts of gender and sex

In general discussions, the concept of gender is often confused with the concept of sex, and the terms are used interchangeably. The meanings of these two concepts are not the same: sex is based on the biological attributes of men and women (chromosomes, anatomy, hormones), while gender is a social construction whereby a society or culture assigns certain tendencies or behaviors to the labels of masculine or feminine. These assignments may differ across cultures and among people within a culture, and even across time. Gender may or may not correspond directly to sex--depending on the society or culture or period. That means, for example, that people may associate themselves with femininity (as defined by their culture) while being biologically male. At the Census Bureau, the sex question wording very specifically intends to capture a person's biological sex and not gender. Ambiguity of these two concepts interferes with accurately and consistently measuring what we intend to measure--the sex composition of the population.

Contact Us

For assistance, please contact the Census Call Center at 1-800-923-8282 (toll free) or visit ask.census.gov for further information.

Page Last Revised - December 16, 2021
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