Data Dictionary: Census 2000
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Survey: Census 2000
Data Source: U.S. Census Bureau
Table: PCT12. Sex By Age [209]
Universe: Total population
Table Details
PCT12. Sex By Age
Universe: Total population
Variable Label
PCT012001
PCT012002
PCT012003
PCT012004
PCT012005
PCT012006
PCT012007
PCT012008
PCT012009
PCT012010
PCT012011
PCT012012
PCT012013
PCT012014
PCT012015
PCT012016
PCT012017
PCT012018
PCT012019
PCT012020
PCT012021
PCT012022
PCT012023
PCT012024
PCT012025
PCT012026
PCT012027
PCT012028
PCT012029
PCT012030
PCT012031
PCT012032
PCT012033
PCT012034
PCT012035
PCT012036
PCT012037
PCT012038
PCT012039
PCT012040
PCT012041
PCT012042
PCT012043
PCT012044
PCT012045
PCT012046
PCT012047
PCT012048
PCT012049
PCT012050
PCT012051
PCT012052
PCT012053
PCT012054
PCT012055
PCT012056
PCT012057
PCT012058
PCT012059
PCT012060
PCT012061
PCT012062
PCT012063
PCT012064
PCT012065
PCT012066
PCT012067
PCT012068
PCT012069
PCT012070
PCT012071
PCT012072
PCT012073
PCT012074
PCT012075
PCT012076
PCT012077
PCT012078
PCT012079
PCT012080
PCT012081
PCT012082
PCT012083
PCT012084
PCT012085
PCT012086
PCT012087
PCT012088
PCT012089
PCT012090
PCT012091
PCT012092
PCT012093
PCT012094
PCT012095
PCT012096
PCT012097
PCT012098
PCT012099
PCT012100
PCT012101
PCT012102
PCT012103
PCT012104
PCT012105
PCT012106
PCT012107
PCT012108
PCT012109
PCT012110
PCT012111
PCT012112
PCT012113
PCT012114
PCT012115
PCT012116
PCT012117
PCT012118
PCT012119
PCT012120
PCT012121
PCT012122
PCT012123
PCT012124
PCT012125
PCT012126
PCT012127
PCT012128
PCT012129
PCT012130
PCT012131
PCT012132
PCT012133
PCT012134
PCT012135
PCT012136
PCT012137
PCT012138
PCT012139
PCT012140
PCT012141
PCT012142
PCT012143
PCT012144
PCT012145
PCT012146
PCT012147
PCT012148
PCT012149
PCT012150
PCT012151
PCT012152
PCT012153
PCT012154
PCT012155
PCT012156
PCT012157
PCT012158
PCT012159
PCT012160
PCT012161
PCT012162
PCT012163
PCT012164
PCT012165
PCT012166
PCT012167
PCT012168
PCT012169
PCT012170
PCT012171
PCT012172
PCT012173
PCT012174
PCT012175
PCT012176
PCT012177
PCT012178
PCT012179
PCT012180
PCT012181
PCT012182
PCT012183
PCT012184
PCT012185
PCT012186
PCT012187
PCT012188
PCT012189
PCT012190
PCT012191
PCT012192
PCT012193
PCT012194
PCT012195
PCT012196
PCT012197
PCT012198
PCT012199
PCT012200
PCT012201
PCT012202
PCT012203
PCT012204
PCT012205
PCT012206
PCT012207
PCT012208
PCT012209
Relevant Documentation:
Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 1: Technical Documentation, 2001.
 
Sex
The data on sex were derived from answers to a question that was asked of all people. Individuals were asked to mark either "male" or "female" to indicate their sex. For most cases in which sex was not reported, it was determined by the appropriate entry 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. (For more information on imputation, see "Accuracy of the Data.")

Sex ratio
A measure derived by dividing the total number of males by the total number of females and multiplying by 100.

Comparability
A question on the sex of individuals has been asked of the total population in every census.
For more information on sex, please telephone 301-457-2378.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 1: Technical Documentation, 2001.
 
Age
The data on age were derived from answers to a question that was asked of all people. The age classification is based on the age of the person in complete years as of April 1, 2000. The age of the person was usually derived from their date of birth information. Their reported age was used only when date of birth information was unavailable.

Data on age are used to determine the applicability of some of the sample questions for a person and to classify other characteristics in census tabulations. Age data are needed to interpret most social and economic characteristics used to plan and examine many programs and policies.

Median age
This measure divides the age distribution into two equal parts: one-half of the cases falling below the median value and one-half above the value. Median age is computed on the basis of a single year of age distribution.

Limitation of the data
The most general limitation for many decades has been the tendency of people to overreport ages or years of birth that end in zero or five. This phenomenon is called "age heaping." In addition, the counts in the 1970 and 1980 censuses for people 100 years old and over were substantially overstated. So also were the counts of people aged 69 in 1970 and aged 79 in 1980. Improvements have been made since then in the questionnaire design, and in the allocation procedures which have further minimized these problems. The count of people aged 89 in the 1990 census was not overstated.

Review of detailed 1990 census information indicated that respondents tended to provide their age as of the date they completed the questionnaire, not their age as of April 1, 1990. One reason this happened was that respondents were not specifically instructed to provide their age as of April 1, 1990. Another reason was that data collection efforts continued well past the census date. In addition, there may have been a tendency for respondents to round their age up if they were close to having a birthday. It is likely that approximately 10 percent of people in most age groups were actually one year younger. For most single years of age, the misstatements were largely offsetting. The problem is most pronounced at age zero because people lost to age one probably were not fully offset by the inclusion of babies born after April 1, 1990. Also, there may have been more rounding up to age one to avoid reporting age as zero years. (Age in complete months was not collected for infants under age one.)

The reporting of age one year older than true age on April 1, 1990, is likely to have been greater in areas where the census data were collected later in calendar year 1990. The magnitude of this problem was much less in the 1960, 1970, and 1980 censuses where age was typically derived from respondent data on year of birth and quarter of birth.

These shortcomings were minimized in Census 2000 because age was usually calculated from exact date of birth and because respondents were specifically asked to provide their age as of April 1, 2000. (For more information on the design of the age question, see the section below that discusses "Comparability.")

Comparability
Age data have been collected in every census. For the first time since 1950, the 1990 data were not available by quarter year of age. This change was made so that coded information could be obtained for both age and year of birth. In 2000, each individual has both an age and an exact date of birth. In each census since 1940, the age of a person was assigned when it was not reported. In censuses before 1940, with the exception of 1880, people of unknown age were shown as a separate category. Since 1960, assignment of unknown age has been performed by a general procedure described as "imputation." The specific procedures for imputing age have been different in each census. (For more information on imputation, see "Accuracy of the Data.")
For more information on age, please telephone 301-457-2428.