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Scientific Data Documentation
Population Data From The 1990 Census

    Some 1990 Census files have been modified for age and race         
    STF1A, SAS File 1990                                               
    CC36.SAS606.STF1A90.STATES) has NOT been modified.                
    STF1A, complete Count Pop & Housing Data, 1990                     
    CC36.CENSUS.STF1A.XX  : XX=State abbreviation)                    
    has NOT been modified.                                            
    Pop. Data from the 1990 Census                                     
    (CC36.CENSUS90.MOD) has been modified                              
    Population Data from the 1990 Census, SAS Files                    
    CC36.SAS.CENSUS.STCTY90 (CTY90)    has been modified             
    CC36.SAS.CENSUS.STCTY90 (STATES90) has been modified             

General Information


 The accompanying tables provide age, sex, race, and Hispanic
 origin data from the 1990 census; as well as similar information
 from a special census file where the age and race data have been
 "modified" to meet the needs of many users of census data.
 Essentially the race statistics were modified to be consistent
 with the classification used in data sets other than the census,
 while the age data were adjusted to correspond with the April 1,
 1990 census date.  These "modified" data are consistent 
 with the counts of the 1990 census as enumerated.  More detailed
 information for smaller geographic units should be released on
 computer tapes and diskettes later this year by the Data Users
 Services Division.

Race Modification

 There were 9,804,847 "Other race" persons included in the 
 1990 census.  These people were not included in one of the 15 racial
 categories listed on the census form.  Such "non-specified" 
 race persons are not found in data sources other than the census.  
 The existence of this group is also inconsistent with the race
 categories defined by the Office of Management and Budget in OMB
 Directive 15.  In order to serve the needs of some portions of
 the user community it is necessary to assign each of these
 persons to a specified race.

 After evaluating many alternatives, the following race assignment
 rule was used:  Assign each "Other race" person to the 
 specified race reported by a nearby person with an identical 
 response to the Hispanic origin question.  The only alternative
 specifications which yielded significantly different National
 results were those where responses to the Hispanic origin
 question were ignored during the assignment of race.  This work
 was done separately for each of the 449 district offices.

 Background Information on the Race Assignment Rule

 1.  The specific Hispanic origin of each "Other race" 
     person in the 1990 census was taken into account when assigning 
     them to a specified race.  This was considered appropriate
     because over 95 percent of the "Other race" persons 
     were of Hispanic origin.  Their origin response was used, whether
     or not it had been allocated, in order to preserve the
     race distribution within each type of origin.  The specific
     Hispanic origin responses were "not Spanish/Hispanic,
     Mexican, Puerto Rican, Cuban, and other Spanish/Hispanic".

 2.  Virtually every person who reported both a specified race
     and an origin was included in the "donor pool" of 
     eligible persons.  The sole exception was the exclusion of 
     several non-specific American Indian codes from the donor pool.
     These codes were: 548-Amerind White, 549--Amerind Black,
     597 and 598--American Indian (general response), and
     973--FOSDIC circle with no write-in response.  These were
     excluded because of evidence from the 1980 census that
     misreporting of rtace was much higher in these codes than it
     was in codes representing specific American Indian tribes.
     Consistent with advisory committee recommendations, any person
     assigned to the American Indian race was given code 973 rather than
     a specific tribal code.

 3.  The assignment of a specified race was made on an
     individual basis.  That is, no effort was made to minimize
     racial heterogeneity within households.  Any such attempt
     would have made it difficult to assign race in a manner
     which approximated the specified-race distribution reported
     by persons with the same Hispanic origin response.

 4.  The race, origin, or sex of some persons also changed as a
     result of the assignment of a different age to them during
     the application of the age modification procedures.  Their
     changed age sometimes caused the person to be allocated a
     different relationship and/or sex which resulted in the
     person receiving their race or origin from a different
     person in the household (Since those items were allocated
     according to hierarchy of relationships).

 5.   The results of the race modification procedures were
      overridden in four counties where the American Indian
      population grew by more than 100 percent and also became at
      least one percentage point more of the county's population:
      Adams County, Washington; Harmon County, Oklahoma; Clark
      County, Idaho; and Washington County, Idaho.  In each case
      the persons were made White.

 6.   In most census allocation procedures, acceptable data from
      eligible persons (donors) are far more common than are the
      cases where the value is assigned to persons without the
      characteristic (the donees).  This means information from
      any given donor is rarely used more than once.  However,
      such large donor-to-donee ratios were not usual here.
      There were a number of occasions where those needing a
      specified race outnumbered those who reported the same
      origin as well as a specified race.
      Special procedures were adopted to minimize the distortions
      produced by such low ratios of donors to donees in some
      cells of these matrices.  The most important change was to
      expand each cell of every allocation matrix to hold 64
      values, rather than the 8 stored in most 1990 census
      matrices.  For each district office, the initial race data
      were then obtained by running the actual census file and
      storing up to the first 64 acceptable cases in each data
      cell.  If the district office did not have 64 cases the
      remaining values were assumed to be White.  After the
      matrices were so "warmed", the program went back to the
      beginning of the data and began the race assignments.  The
      actual race assignment was a random selection from the
      unused values within each cell.  If all 64 values had been
      used, then assignment was random from among all 64 until
      new acceptable cases were available.  Used values in a cell
      were replaced with acceptable data in reverse of the order
      of use.

Age Modification

 The following is a portion of the text of a user note which is
 incorporated in 1990 census products:

 "Age Reporting -- Review of detailed 1990 information indicated
 that respondents tended to provide their age as of the date of
 completion of the questionnaire, not their age as of April 1,
 1990.  In addition, there may have been a tendency for
 respondents to round up their age if they were close to having a
 birthday.  It is likely that approximately 10 percent of persons
 in most age groups are actually 1 year younger.  For most single
 years of age, the misstatements are largely offsetting.  The
 problem is most pronounced at age 0 because persons lost to age 1
 may not have been fully offset by the inclusion of babies born
 after April 1, 1990 and because there may have been more rounding
 up to age 1 to avoid reporting age as 0 years.  (Age in completed
 months was not collected for infants under age 1.)
   The reporting of age 1 year older than age on April 1, 1990 is
 likely to have been greater in areas where the census data were
 collected later in 1990."

 About 95 percent of the population provided acceptable birth year
 responses which were adjusted with the following procedures.  The
 age data for individuals in households were modified by adjusting
 the reported birth year data by race and sex for each of the
 1990 Census 49 district offices to correspond with the national
 level quarterly distribution of births available from the
 national Center for Health Statistics.  The data for persons in
 group quarters were adjusted on a state basis to minimize the
 number of matrix cells with very small numbers.  The central
 assumption in this procedure is that there is no reason for the
 residents of any subnational area to have a different quarter of
 birth distribution from that found at the national level.  It was
 also assumed that there are no significant birth place-sex-race-
 origin differences in annual birth distributions by quarter, that
 all those born before 1920 have the same quarter of birth
 distribution, and that mortality is not selective by quarter of
 birth.  Approximately 100 million persons have an age in this
 modified file which is one year different from that they had in
 the 1990 census.

 The nodification procedure was done separately for each birth
 year, by sex, for the White; Black; Asian or Pacific Islander;
 and American Indian, Eskimo, or Aleut populations.  For every
 birth year the program was provided with the number of cases out
 of 10,000 where the birth year plus the person's age should equal
 1989 (most years that number was close to 7,500).  These overall
 control values were calculated from the available monthly birth
 statistics for the 1920 to 1989 period.  Earlier birth years were
 each assumed to have the same seasonal pattern as was exhibited
 by the unweighted average of the 1920-24 birth cohorts.  Each
 sex-race-origin cell was next randomly assigned a value of 0,
 0.25, 0.5, or 0.75.  Then, each time that birth year cell was
 encountered, a test was made to see if that birth year plus the
 person's age should equal 1989 or 1990.  The choice of an age was
 dependent on whether its acceptance moved the cell's actual
 population distribution toward the control value distribution.

 Character             Item Description
 ---------             -----------------
    1-2                FIPS State Code
    3-5                Fips County Code
      6                Blank

        Age = Under 1 year:

   7-15                Hispanic Male: White
  16-24                Hispanic Male: Black
  25-33                Hispanic Male: American Indian, Eskimo, and Aleut
  34-42                Hispanic Male: Asian and Pacific Islander
  43-51                Hispanic Female: White
  52-60                Hispanic Female: Black
  61-69                Hispanic Female: American Indian, Eskimo, and Aleut
  70-78                Hispanic Female: Asian and Pacific Islander
  79-87                Not Hispanic Male: White
  88-96                Not Hispanic Male: Black
  97-105               Not Hispanic Male: American Indian, Eskimo, and Aleut
 106-114               Not Hispanic Male: Asian and Pacific Islander
 115-123               Not Hispanic Female: White
 124-132               Not Hispanic Female: Black
 133-141               Not Hispanic Female: American Indian, Eskimo, and Aleut
 142-150               Not Hispanic Female: Asian and Pacific Islander
        Age = 1 year:
 151-294               Repeat Hispanic Origin, Sex, Race cells as above
        Age = 2 years:
 295-438               Repeat Hispanic Origin, Sex, Race cells as above
        Age = 3 years:
 439-582               Repeat Hispanic Origin, Sex, Race cells as above
        .              Repeat for single years of age
        .               (All data cells are 9 characters each)
        Age = 98 years:
 14119-14262           Repeat Hispanic Origin, Sex, Race cells as above
        Age = 99 years:
 14263-14406           Repeat Hispanic Origin, Sex, Race cells as above
        Age = 100 years:
 14407-14550           Repeat Hispanic Origin, Sex, Race cells as above

This page last reviewed: Thursday, January 28, 2016
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