Data Dictionary: ACS 2008 (1-Year Estimates)
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Data Source: U.S. Census Bureau
Universe: Total population
Variable Details
B01001. Sex By Age
Universe: Total population
B01001028 5 to 9 years
Aggregation method:
Addition
Relevant Documentation:
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Sex
The data on sex were derived from answers to Question 3. Individuals were asked to mark either "male" or "female" to indicate their sex. For most cases in which sex was not reported, the appropriate entry was determined from the persons given (i.e., first) name and household relationship. Otherwise, sex was imputed according to the relationship to the householder and the age of the person.
Sex Ratio
The sex ratio represents the balance between the male and female populations. Ratios above 100 indicate a larger male population, and ratios below 100 indicate a larger female population. This measure is derived by dividing the total number of males by the total number of females and then multiplying by 100. It is rounded to the nearest tenth.
Limitation of the data
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations have sex distributions that are very different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the sex distribution. This is particularly true for areas with a substantial GQ population.

The Census Bureau tested the changes introduced to the 2008 version of the sex question in the 2007 ACS Grid-Sequential Test (http://www.census.gov/acs/www/Downloads/ACS-MP-09_Grid-Sequential_Test_Final_Report.pdf). The results of this testing show that the changes may introduce an inconsistency in the data produced for this question as observed from the years 2007 to 2008.
Question/Concept History
Beginning in 2008, the layout of the sex question response categories was changed to a horizontal side-by-side layout from a vertically stacked layout on the mail paper ACS questionnaire.
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Age
The data on age were derived from answers to Question 4. The age classification is based on the age of the person in complete years at the time of interview. Both age and date of birth are used in combination to calculate the most accurate age at the time of the interview. Inconsistently reported and missing values are assigned or imputed based on the values of other variables for that person, from other people in the household, or from people in other households ("hot deck" imputation). Data on age are used to determine the applicability of other questions for a particular individual and to classify other characteristics in tabulations. Age data are needed to interpret most social and economic characteristics used to plan and analyze programs and policies. Therefore, age data are tabulated by many different age groupings, such as 5-year age groups.
Median Age
The median age is the age that divides the population into two equal-size groups. Half of the population is older than the median age and half is younger. Median age is based on a standard distribution of the population by single years of age and is shown to
the nearest tenth of a year. (See the sections on "Standard Distributions" and "Medians" under "Derived Measures.")
Age Dependency Ratio
The age dependency ratio is derived by dividing the combined under-18 and 65-and-over populations by the 18-to-64 population and multiplying by 100.
Old-Age Dependency Ratio
The old-age dependency ratio is derived by dividing the population 65 years and over by the 18-to-64 population and multiplying by 100.
Child Dependency Ratio
The child dependency ratio is derived by dividing the population under 18 years by the 18-to-64 population, and multiplying by 100.
Limitation of the Data
Caution should be taken when comparing population in age groups across time. The entire population continually ages into older age groups over time and babies fill in the youngest age group. Therefore, the population of a certain age is made up of a completely different group of people in 2000 and 2008. Since populations occasionally experience booms/increases and busts/decreases in births, deaths, or migration (for example, the postwar Baby Boom from 1946-1964), one should not necessarily expect that the population in an age group in Census 2000 should be similar in size or proportion to the population in the same age group in the 2008 ACS. For example, Baby Boomers were age 36 to 54 in Census 2000 while they were age 44 to 62 in the 2008 ACS. Therefore, the age group 55 to 59 would show a considerable increase in population when comparing Census 2000 data with the 2008 ACS data. Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations have age distributions that are very different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the age distribution. This is particularly true for areas with a substantial GQ population.
Question/Concept History
The 1996-2002 American Community Survey question asked for month, day, and year of birth before age. Since 2003, the American Community Survey question asked for age, followed by month, day, and year of birth. In 2008, an additional instruction was provided with the age and date of birth question on the American Community Survey questionnaire to report babies as age 0 when the child was less than 1 year old. The addition of this instruction occurred after 2005 National Census Test results indicated increased accuracy of age reporting for babies less than one year old.