Data Dictionary: Census 1990
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Survey: Census 1990
Data Source: U.S. Census Bureau
Table: H77. Imputation Of Year Structure Built [3]
Universe: Housing units
Table Details
H77. Imputation Of Year Structure Built
Universe: Housing units
Variable Label
H077_001
H077_002
H077_003
Relevant Documentation:
Excerpt from: Social Explorer, U.S. Census Bureau; Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine-readable data files] / prepared by the Bureau of the Census. Washington: The Bureau [producer and distributor], 1991.
 
Confidentiality of the Data
To maintain the confidentiality required by law (Title 13, United States Code), the Bureau of the Census applies a confidentiality edit to the 1990 census data to assure that published data do not disclose information about specific individuals, households, or housing units. As a result, a small amount of uncertainty is introduced into the estimates of census characteristics. The sample itself provides adequate protection for most areas for which sample data are published since the resulting data are estimates of the actual counts; however, small areas require more protection. The edit is controlled so that the basic structure of the data is preserved.

The confidentiality edit is implemented by selecting a small subset of individual households from the internal sample data files and blanking a subset of the data items on these household records. Responses to those data items were then imputed using the same imputation procedures that were used for nonresponse. A larger subset of households is selected for the confidentiality edit for small areas to provide greater protection for these areas. The editing process is implemented in such a way that the quality and usefulness of the data were preserved.

Excerpt from: Social Explorer, U.S. Census Bureau; Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine-readable data files] / prepared by the Bureau of the Census. Washington: The Bureau [producer and distributor], 1991.
 
Editing of Unacceptable Data
The objective of the processing operation is to produce a set of data that describes the population as accurately and clearly as possible. To meet this objective, questionnaires were edited during field data collection operations for consistency, completeness, and acceptability. Questionnaires also were reviewed by census clerks for omissions, certain specific inconsistencies, and population coverage. For example, write-in entries such as Dont know or NA were considered unacceptable. For some district offices, the initial edit was automated; however, for the majority of the district offices, it was performed by clerks. As a result of this operation, a telephone or personal visit followup was made to obtain missing information. Potential coverage errors were included in the followup, as well as a sample of questionnaires with omissions and/or inconsistencies. Subsequent to field operations, remaining incomplete or inconsistent information on the questionnaires was assigned using imputation procedures during the final automated edit of the collected data. Imputations, or computer assignments of acceptable codes in place of unacceptable entries or blanks, are needed most often when an entry for a given item is lacking or when the information reported for a person or housing unit on that item is inconsistent with other information for that same person or housing unit. As in previous censuses, the general procedure for changing unacceptable entries was to assign an entry for a person or housing unit that was consistent with entries for persons or housing units with similar characteristics. The assignment of acceptable codes in place of blanks or unacceptable entries enhances the usefulness of the data.

Another way in which corrections were made during the computer editing process was through substitution; that is, the assignment of a full set of characteristics for a person or housing unit. When there was an indication that a housing unit was occupied but the questionnaire contained no information for the people within the household or the occupants were not listed on the questionnaire, a previously accepted household was selected as a substitute, and the full set of characteristics for the substitute was duplicated. The assignment of the full set of housing characteristics occurred when there was no housing information available. If the housing unit was determined to be occupied, the housing characteristics were assigned from a previously processed occupied unit. If the housing unit was vacant, the housing characteristics were assigned from a previously processed vacant unit.

Table A. Unadjusted Standard Error for Estimated Totals [Based on a 1-in-6 simple random sample]
Estimated Total Size of publication area2
500 1,000 2,500 5,000 10,000 25,000 50,000 100,000 250,000 500,000 1,000,000 5,000,000 10,000,000 25,000,000
50 16 16 16 16 16 16 16 16 16 16 16 16 16 16
100 20 21 22 22 22 22 22 22 22 22 22 22 22 22
250 25 30 35 35 35 35 35 35 35 35 35 35 35 35
500   35 45 45 50 50 50 50 50 50 50 50 50 50
1,000     55 65 65 70 70 70 70 70 70 70 70 70
2,500       80 95 110 110 110 110 110 110 110 110 110
5000         110 140 150 150 160 160 160 160 160 160
10,000           170 200 210 220 220 220 220 220 220
15,000           170 230 250 270 270 270 270 270 270
25,000             250 310 340 350 350 350 350 350
75,000               310 510 570 590 610 610 610
100,000                 550 630 670 700 700 710
250,000                   790 970 1 090 1 100 1 100
500,000                     1120 1 500 1 540 1 570
1,000,000                       2 000 2 120 2 190
5,000,000                         3 540 4 470
10,000,000                           5 480


Footnote:
1For estimated totals larger than 10,000,000, the standard error is somewhat larger than the table values. The formula given below should be used to calculate the standard error.

2The total count of persons in the area if the estimated total is a person characteristic, or the total count of housing units in the area if the estimated total is a housing unit characteristic.



Table B. Unadjusted Standard Error in Percentage Points for Estimated Percentage [Based on a 1 in-6 simple random sample]
Estimated percentage Base of percentage1
500 750 1,000 1,500 2,500 5,000 7,500 10,000 25,000 50,000 100,000 250,000 500,000
2 or 98 1.4 1.1 1.0 0.8 0.6 0.4 0.4 0.3 0.2 0.1 0.1 0.1 0.1
5 or 95 2.2 1.8 1.5 1.3 1.0 0.7 0.6 0.5 0.3 0.2 0.2 0.1 0.1
10 or 90 3.0 2.4 2.1 1.7 1.3 0.9 0.8 0.7 0.4 0.3 0.2 0.1 0.1
15 or 85 3.6 2.9 2.5 2.1 1.6 1.1 0.9 0.8 0.5 0.4 0.3 0.2 0.1
20 or 80 4.0 3.3 2.8 2.3 1.8 1.3 1.0 0.9 0.6 0.4 0.3 0.2 0.1
25 or 75 4.3 3.5 3.1 2.5 1.9 1.4 1.1 1.0 0.6 0.4 0.3 0.2 0.1
30 or 70 4.6 3.7 3.2 2.6 2.0 1.4 1.2 1.0 0.6 0.5 0.3 0.2 0.1
35 or 65 4.8 3.9 3.4 2.8 2.1 1.5 1.2 1.1 0.7 0.5 0.3 0.2 0.2
50 5.0 4.1 3.5 2.9 2.2 1.6 1.3 1.1 0.7 0.5 0.4 0.2 0.2


Footnote:
1For a percentage and/or base of percentage not shown in the table, the formula given below may be used to calculate the standard error. This table should only be used for proportions, that is, where the numerator is a subset of the denominator.



Excerpt from: Social Explorer, U.S. Census Bureau; Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine-readable data files] / prepared by the Bureau of the Census. Washington: The Bureau [producer and distributor], 1991.
 
Year Structure Built
The data on year structure built were obtained from questionnaire item H17, which was asked at both occupied and vacant housing units. This item was asked on a sample basis. Data on year structure built refer to when the building was first constructed, not when it was remodeled, added to, or converted. For housing units under construction that met the housing unit definition--that is, all exterior windows, doors, and final usable floors were in place--the category "1989 or March 1990" was used. For a houseboat or a mobile home or trailer, the manufacturer's model year was assumed to be the year built. The figures shown in census data products relate to the number of units built during the specified periods that were still in existence at the time of enumeration.

Median Year Structure Built
The median divides the distribution into two equal parts. The median is rounded to the nearest calendar year. Median age of housing can be obtained by subtracting median year structure built from 1990. For example, if the median year structure built is 1957, the median age of housing in that area is 33 years (1990 minus 1957).

Limitation of the Data--Data on year structure built are more susceptible
to errors of response and nonreporting than data on many other items because respondents must rely on their memory or on estimates by persons who have lived in the neighborhood a long time. Available evidence indicates there is underreporting in the older-year-structure- built categories, especially "Built in 1939 or earlier." The introduction of the "Don't know" category (see the discussion on "Comparability") may have resulted in relatively higher allocation rates. Data users should refer to the discussion in Appendix C, Accuracy of the Data, and to the allocation tables.
Comparability--Data on year structure built were collected for the first
time in the 1940 census. Since then, the response categories have been modified to accommodate the 10-year period between each census. In 1990, the category, "Don't Know," was added in an effort to minimize the response error mentioned in the paragraph above on limitation of the data.