Abirth rate is
calculated by dividing the number of live births in a population in a year
by the midyear resident population. For census years, rates are based on unrounded census counts of the resident population, as of April 1. For the
noncensus years 1981-89, rates were based on national estimates of the
resident population, as of July 1, rounded to 1,000s. Rounded population
estimates for 5-year age groups were calculated by summing unrounded
population estimates before rounding to 1,000s. Starting in 1991 rates
were based on unrounded national population estimates. Beginning in 1997
the birth rate for the maternal age group 45-49 years includes data for
mother's age 50-54 years in the numerator and is based on the population
of women 45-49 years in the denominator. Birth rates are expressed as the
number of live births per 1,000 population. The
rate may be restricted to births to women of specific age, race, marital
status, or geographic location (specific rate), or it may be related to
the entire population (crude
rate).
A
death rateis
calculated by dividing the number of deaths in a population in a year by
the midyear resident population. For census years, rates are based on
unrounded census counts of the resident population, as of April 1. For the
noncensus years 1981-89, rates were based on national estimates of the
resident population, as of July 1, rounded to 1,000s. Rounded population
estimates for 10-year age groups were calculated by summing unrounded
population estimates before rounding to 1,000s. Starting in 1991 rates
were based on unrounded national population estimates. Rates for the
Hispanic and non-Hispanic white populations in each year are based on
unrounded State population estimates for States in the Hispanic reporting
area. Death rates are expressed as the number of deaths per 100,000
population. The
rate may be restricted to deaths in specific age, race, sex, or geographic
groups or from specific causes of death (specific rate) or it may be
related to the entire population (crude rate).
A fetal death rate
is the number of fetal deaths with stated or presumed gestation of 20
weeks or more divided by the sum of live births plus fetal deaths,
per 1,000 live births plus fetal deaths.
A
late fetal death rate is the number of fetal deaths with
stated or presumed gestation of 28 weeks or more divided by the sum
of live births plus late fetal deaths, per 1,000 live births plus late
fetal deaths.
An
infant
mortality rate is based on period files calculated by
dividing the number of infant deaths during a calendar year by the number of live births reported in the same year. It is
expressed as the
number of infant deaths per 1,000 live births.
A
neonatal mortality rate is the number of deaths of children under 28 days of
age, per 1,000 live births.
A
postneonatal mortality rate is the number of deaths of
children that occur between 28 days and 365 days after birth, per 1,000
live births.
Birth cohort infant mortality rates
are based on linked birth and infant death files. In contrast to period
rates in which the births and infant deaths occur in the same period or
calendar year, infant deaths comprising the numerator of a birth cohort
rate may have occurred in the same year as, or in the year following the
year of birth. The birth cohort infant mortality rate is expressed as the
number of infant deaths per 1,000 live births.
Perinatal
mortality rate is the sum of late fetal deaths plus infant deaths
within 7 days of birth divided by the sum of live births plus late fetal
deaths, per 1,000 live births plus late fetal deaths. (Perinatal relates to the period surrounding the birth
event. Rates and
ratios are based on events reported in a calendar year.) Perinatal mortality ratio
is the sum of late fetal deaths plus infant deaths within 7 days of birth
divided by the number of live births, per 1,000 live births.
Maternal
mortality
rate
is
defined as the number of maternal deaths per 100,000 live births. The
maternal mortality rate is a measure of the likelihood that a pregnant
woman will die from maternal causes. The number of live births used in the
denominator is a proxy for the population of pregnant women who are at
risk of a maternal death.
Hospital
occupancy rate is defined by the American Hospital Associationas
the average daily census divided by the number of hospital beds, cribs,
and pediatric bassinets set up and staffed on the last day of the
reporting period, expressed as a percent. Average daily census is
calculated by dividing the total annual number of inpatients, excluding
newborns, by 365 days to derive the number of inpatients receiving care on
an average day during the annual reporting period.
Facility
occupancy rate for
facilities other than hospitals is calculated as the number of residents
at the facility reported on the day of the interview divided by the number
of reported beds. In the Online Survey Certification and Reporting
Database, occupancy is determined as of the day of certification
inspection as the total number of residents on that day divided by the
total number of beds on that day.
Relative survival rate is the
ratio of the
observed survival rate for the patient group to the expected survival
rate for persons in the general population similar to the patient group
with respect to age, sex, race, and calendar year of observation. The
5-year relative survival rate is used to estimate the proportion of
cancer patients potentially curable. Because over one-half of all
cancers occur in persons 65 years of age and over, many of these
individuals die of other causes with no evidence of recurrence of their cancer.
Thus, because it is obtained by adjusting observed survival for the
normal life expectancy of the general population of the same age, the
relative survival rate is an estimate of the chance of
surviving the effects of cancer.
Fertility rate is the total number of live births, regardless of age of
mother, per 1,000 women of reproductive age,
15-44 years.
SOURCE:
Health, United States
Total
fertility rate (TFR) shows the potential
impact of current fertility patterns on reproduction, that is, completed
family size. The TFR indicates the average number of births to a hypothetical cohort of
1,000 women, if they experienced throughout their childbearing years the
age-specific birth rates observed in a given year. Because it is based on
age-specific birth rates, the TFR is not affected by changes over time in
the age composition of a population and can be used to compare populations
over time or between different groups.
Gross
reproduction rate
(GRR)
represents the average number of daughters born to a hypothetical cohort of
1,000 women if they experienced the age-specific birth rates observed in a
given year throughout their childbearing years and if none of the cohort was
to die during her childbearing years. The GRR is similar to the
total fertility rate (TFR)
except that it measures only female births, since reproduction is largely
dependent on the number of females in a given population. Moreover, like the
TFR, the GRR is age adjusted and thus rates can be compared over time or
between different groups.
Net
reproduction rate
(NRR) is closely related to the gross reproduction
rate (GRR). However, unlike the GRR, the NRR incorporates the
effects of mortality. The NRR represents the average number of
daughters who would be born to a hypothetical cohort of 1,000 women, if they
passed through their childbearing years conforming to the age-specific
fertility and mortality rates of a given year. In contrast, the GRR
assumes that all of the women in the cohort survive through their
childbearing years.
The
intrinsic rate of natural increase measures the rate of
population growth that would eventually result from the continuance of the
age-specific birth and mortality rates of a given year over a long period of
time, assuming no migration. Because it is based on age-specific birth and
mortality rates, the intrinsic rate of natural increase is not affected by
changes over time in the age composition of a population. A rate that is
less than zero (negative) signifies a population decline, whereas a rate
greater than zero (positive) denotes population growth.
The intrinsic rates are calculated based on a stable
population. A stablepopulation is a hypothetical
population that would eventually result from the continuance of the
age-specific fertility and mortality rates of a given year over a long
period of time, assuming no migration.
The intrinsic birth rate
is
the birth rate of a stable population. The intrinsic death rate
is the death rate of a stable population.