1. Population and Demographic Data
Different Rates
Homework: 
Today’s Topics:
Crude Birth Rate
General Fertility Rate
Age-specific Birth Rate
Total Fertility Rate
Lecture no. -12

2. Crude Birth Rate
The simplest and most common measure of natality is the crude birth rate. The crude birth rate is defined as the number of births in a year per 1000 midyear population—that is,

3. General Fertility Rate
The simplest overall age-limited measure is the general fertility rate, defined as the number of births per 1000 women of childbearing age. It may be represented by The total number of births, regardless of age of mother, is employed in the numerator and the female population 15 to 44 years of age is employed in the denominator.

4. Age-Specific Birth Rate
An age-specific birth rate is defined as the number of births to women of a given age group per 1000 women in that age group: A set of rates may consist of the rates for 5-year age groups from 10–14 to 45–49, 15–19 to 45–49, or 15–19 to 40–44.

5. Age-Specific Birth Rate
The formula for the birth rate at ages 20 to 24 is

6. Total Fertility Rate
The total fertility rate (TFR) is another measure of fertility. The total fertility rate represents simply the sum of the age-specific birthrates over all ages of the childbearing period. If the actual rates are for single years of age, then they each receive a weight of 1; if the actual rates are for 5-year age groups, as is the usual case, then they each receive a weight of 5.

7. Total Fertility Rate
In the latter case, the calculation is simply carried out by summing the rates and multiplying the total by 5:

8. Decomposition of Difference between Rates
To demonstrate the usefulness of this method, we will consider the relatively simple example of the crude birth rate expressed as the product of age-specific birth rates and the proportion of women in specific age categories relative to the total population, as shown in the following equation: where B equals total births, represents births to women of a given age group, equals the female population in age groups, and P is the total population.

9. Question???