METHODOLOGY for ESTIMATES of STATE POPULATION by AGE and SEX 

Source:  U.S. Bureau of the Census
Release date:  June, 1999


Extracted from P25-1127

The state age-sex estimates are produced with a state estimates
model that is a version of Component Method II.  Estimates are
produced for each single year of age by sex up to age 65.  In
this method each age follows the standard demographic formula of
P1 = P0 + B - D + M: where P1 is the population on the estimate
date; P0 is the population on the census date; B and D are the
births and deaths occurring during the estimate period, and M is
the net migration (including international net migration)
occurring during the estimate period.  This is a cumulative
method, where the estimate period is from the date of the last
census to the estimate date.  The steps used in estimating single
years of age (0 to 64) for the civilian population are summarized
below:      

     1.  The resident cohort population by single year of age is
developed by carrying forward the April 1, 1990 census count (for
each age) to the July 1 estimate date;
     2.  Births entering each cohort for the period between 
April 1, 1990 and the July 1 estimate date are added where
appropriate;
     3.  An estimate of the Armed Forces cohort population for
each age 17-64 on the estimate date, is subtracted from the 
resident cohort population to create the civilian cohort
population; 
     4.  An estimate of the net civilian migration for 1990 to
the estimate date is added;
     5.  An estimate of the net change in civilian population
entering the Armed Forces population during the estimate period
is added.

The result of these five steps is unadjusted civilian age
estimates, but without sex detail.  Sex detail originates from
the following steps: (1) The 1990 census proportion of male
civilian population is calculated for each year of age by State;
(2) national sex ratios by single year of age are calculated for
both the 1990 census civilian population and for each estimate
year; (3) the change in the national sex ratios between the
estimate year and the census base year are used to update the
1990 State ratios; and (4) these are applied to the State single-
year civilian population estimates for both sexes to obtain
civilian sex detail by age. 

Final steps in the component method for age are to:  (1) adjust
each age-sex cell (0 to 64) to an independent national civilian
population estimate; (2) further adjust each age-sex cell within
a State to the civilian state population total; (3) Add estimates
of Armed Forces by age and sex to the civilian population to
produce resident population. 

The vital statistics used in the age estimates are from the same
sources used in the Federal Tax Returns Method.  The net
migration component revolves around elementary school enrollment
and school-age migration.  It is developed in two age segments: 
(1) State school-age net migration for the estimate period is
used to formulate an amount of net migration for each age under
age 17; and (2) Each state's school-age migration rate is
converted to net migration rates for single years 17 through 64,
then applied to a base (cohort for that age minus 1/2 the deaths
to the cohort) in order to derive net migration amounts.

The Armed Forces data used in this method are obtained from the
Departments of Defense and Transportation.  All military persons
are assumed to be between the ages of 17 and 64.  State Armed
Forces data are not provided by age or sex.  National level data
are used to assign age-sex detail to the States.  The group
quarters data are updated on an annual basis.