This series of reports presents population estimates prepared under the auspices of the Federal-State Cooperative Program for Local Population Estimates. The objective of this program is the development and publication of State-prepared estimates of the population of counties using uniform procedures largely standardized for data input and methodology. The methods used have been mutually agreed upon by the individual States and the Bureau of the Census and were selected on the basis of the results of an extensive test of methods against the 1970 census conducted in late 1971 and early 1972.1

The estimates for July 1, 1971, and provisional estimates for July 1, 1972, shown here for counties in Utah, were prepared by the Utah Department of Employment Security. This agency was designated by the Governor to work with the Bureau of the Census in implementing and carrying out the Federal-State Cooperative Program.

11

For a more detailed description of the program, see Meyer Zitter, "Federal-State Cooperative Program for Local Population Estimates, The Registrar and Statistician, U.S. Department of Health, Education, and Welfare, January 1968, and "Federal-State Cooperative Program for Local Popula

tion Estimates: Status Report, January 1971," The Registrar and Statistician, U.S. Department of Health, Education, and Welfare, April 1971. For a detailed analysis of the test results, forthcoming Current Population Reports, Series P-26, "Federal-State Cooperative Program for Local Population Estimates: Test Results--April 1,

1970.

see the

The estimates shown for July 1, 1971, are based on an average of: (1) the Regression (ratiocorrelation) method, in which a multiple regression equation is used to relate changes in a number of different data series to changes in population distribution. The series of data used in the Regression method for Utah are vital statistics (births plus deaths) (X), work force (X), school enrollment (X), and automobile registration (X4). The prediction equation for Utah for the 1970's is given by

Y-0.0777+ 0.0865X1-0.0300X2 +0.4091X3 +0.4514X4

and (2) The Census Bureau's Component Method II, which employs vital statistics to measure natural increase and school enrollment as a basis for measuring net migration. The estimates made by the Census Bureau's Component Method II are specific to the civilian population under 65, with Medicare statistics used to estimate the resident population ages 65 and over. The total resident population is derived by adding, to the estimates of the civilian resident population, estimates of the military station strength in each county. The county estimates are then adjusted to State Component Method II.2

2A general description of Component Method II and the Regression Method will be given in the forthcoming Current Population Reports, Series P-25, "Estimates of the Population of States, 1971 and 1972, to be published later this year.

The provisional July 1, 1972 estimates were developed by adding the change between 1971 and 1972 Component Method II estimates to the 1971 estimate and adjusting the county estimates to agree with the provisional July 1, 1972, State estimate published in Current Population Reports, Series P-25, No. 488.

Corresponding estimates for other States in the program will be published as they become available. The jointly prepared estimates for counties shown here are presented by the Bureau

of the Census in lieu of preparing competing estimates. These estimates for counties are consistent with independent State population totals regularly prepared by the Bureau of the Census and published in the P-25 series of reports.

The estimates presented in the table have been rounded to the nearest hundred without being adjusted to the State total, which was independently rounded to the nearest thousand. Percentages are based on unrounded numbers.

This series of reports presents population estimates prepared under the auspices of the Federal-State Cooperative Program for Local Population Estimates. The objective of this program is the development and publication of Stateprepared estimates of the population of counties using uniform procedures largely standardized for data input and methodology. The methods used have been mutually agreed upon by the individual States and the Bureau of the Census and were selected on the basis of the results of an extensive test of methods against the 1970 census conducted in late 1971 and early 1972.1

The estimates for July 1, 1971, shown here for counties in Arizona were prepared by The Employment Security Commission of Arizona. This agency was designated by the Governor to work with the Bureau of the Census in implementing and carrying out the Federal-State Cooperative Program.

see

་་

For a more detailed description of the program, Meyer Zitter, "Federal-State Cooperative Program for Local Population Estimates, The Statistician, Registrar and U.S. Department of Health, Education, and Welfare, January 1968, and "Federal-State Cooperative Program for Local Population Estimates: Status Report, January 1971," The Registrar and Statistician, U.S. Department of Health, Education, and Welfare, April 1971. For a detailed analysis of the test results, see the forthcoming Current Population Reports, Series P-26, "Federal-State Cooperative Program for Local Results--April 1, 1970."

Population Estimates:

་་

Test

(3) The Composite method in which estimates of various age groups are derived separately and are then summed to secure a total for all ages. Death statistics are used to estimate the population in ages 45 and over, birth statistics are used to estimate the population in ages 18 to 44 and under 5, and the Census Bureau's Component Method II is used to estimate the population in ages 5 to 17 years. In the case of birth and death statistics, an arithmetic average of two years of data is used for both the base year (1970) and the estimate year (1971). The two year average is used to smooth out. random fluctuations in the data which distort the estimates.

(4) The Housing Unit Method in which the estimates of population are based on estimates of dwelling units. The latter, in turn, are based

on data on building permits issued, or on data on electric, gas, or water meter connections.

2A general description of Component Method II and the Regression Method will be given in the forth

coming Current Population Reports, Series P-25, "Estimates of the Population of States, 1971 and 1972," to be published later this year.

For nonmetropolitan counties, the estimates. are based on an average of the Regression method, Component Method II, and the Composite method.

Corresponding estimates for other States in the program will be published as they become available. The jointly prepared estimates for counties shown here are presented by the Bureau of the Census in lieu of preparing competing estimates. These estimates for counties are consistent with independent State population totals regularly prepared by the Bureau of the Census and published in the P-25 series of reports.

County populations for 1970 reflect corrections in the census count made since tabulations of the census. Counties with corrections of 500 or more are Maricopa and Pinal. The official 1970 resident State total shown on the table may differ slightly from the sum of the counties because of corrections made subsequent to the release of the State figure.

The estimates presented in the table have been rounded to the nearest hundred without being adjusted to the State total, which was independently rounded to the nearest thousand. Percentages are based on unrounded numbers.