Fertility : Fertility Describe the various measures for estimating fertility in a population. Discuss the advantages & disadvantages of each Few issues: please give your comments : Few issues: please give your comments What do you understand by Fertility And Fecundity
Why study fertility or why demography
What are Sources of Data for fertility studies
Difference B/w Rate, Ratio & Proportion
Mid year population ?
Factors affecting fertility ? Describe the various measures for estimating fertility in a population. Discuss the Advantages & Disadvantages of each. : Describe the various measures for estimating fertility in a population. Discuss the Advantages & Disadvantages of each. Crude Birth Rate : Crude Birth Rate Indicates the number of live births per 1,000 population in a given year.
Directly indicates the contribution of births to natural growth rate
Easy to calculate
It has limited analytical utility as it is affected by factors like age-sex structure of population, distribution of married woman in the reproductive period.
In its calculation both the population exposed & not exposed to risk of births are included and hence it doesn’t conform to concepts of probability & is thus a crude measure, Thus it cannot be used to compare levels of fertility in two populations.
It is not very sensitive to small changes in fertility General Fertility Rate : General Fertility Rate The general fertility rate (also called the fertility rate) is the number of live births per 1,000 women ages 15-49** 44 in a given year
Simplest overall age limited measure of fertility as It relates births to the age-sex group at risk of giving birth
We cant compare GFR of two countries directly unless we adjust them for the age distributions of women in reproductive age Age Specific fertility rate : Age Specific fertility rate Number of births per year per woman of a specifies age group; conventionally by quinequennial age group15-19, 20-24, ……
Can be compared over different age groups to see fertility behavior
Can be compared over time for age group to see trends
Can be used to compare populations but Not a composite or summary measure of fertility Total Fertility Rate : Total Fertility Rate Average number of children that would be born to a woman by the time she ended childbearing if she were to pass through all her childbearing years conforming to the age-specific fertility rates of a given year
Can be used over any two populations
TFR is a synthetic measure; no individual woman is very likely to pass through three decades conforming to the age-specific fertility rates of any single year. In reality, age-specific rates change and fluctuate from year to year, even if only gradually.
2. year-to-year fluctuations in the TFR may reflect changes in the timing of births rather than changes in the average number of children women bear, For example, women who were ages 15-19 in 2003 may delay childbearing longer than women ages 15-19 in, say, 1990. They would lower the TFR a bit in 2003 but then raise it several years later when they begin their childbearing Calculating TFR : Calculating TFR *****PLZ DON’T CONFUSE ***** : *****PLZ DON’T CONFUSE ***** Children ever born: number of “children ever born” at various ages of the mother provides one measure of a population’s fertility. This measure is useful only if the age group of women considered is specified. When this measure is calculated for women over age 49,
It is called the completed fertility rate; it shows how many children a certain cohort of women who have completed childbearing actually produced during their childbearing years Other Fertility Rates : Other Fertility Rates Standardized Fertility rates: Like direct & Indirect Standardized Mortality rates, Standardized fertility rates can also be calculated by use of a standard population to facilitate comparisons
Marital fertility rates: General Marital fertility rate & Age specific marital fertility rates: “Married Women” change in denominator , Total marital fertility rate: similar to TFR calculated for married woman.
??? why the issue of marital rates. To reduce crudeness in denominator as married women contribute to most births in many societies like India Contd. : Contd. Birth rate for Unmarried woman: The birth rate of unmarried women is the number of live births by unmarried women per 1,000 unmarried women ages 15-49 years in a given year
Percentage of Births outside marriage:number of live births to unmarried women (never married, widowed, or divorced) per 100 total live births in a given year
**** The percentage of births outside marriage can grow while the rate of births to unmarried women declines or remains stable. This can occur when the proportion of women who are not married increases
**** not applicable in Indian society Contd : Contd Child woman ratio: The child-woman ratio is the number of children under age 5 per 1,000 women of childbearing age in a given year. This measure can be calculated from national censuses or survey data, thereby
providing fertility data where birth statistics may not otherwise be available Reproductive Rates : Reproductive Rates Gross Reproductive Rate:
The gross reproduction rate (GRR) is the average number of daughters that would be born to a woman (or group of women) during her lifetime if she passed through her childbearing years conforming to the age-specific fertility rates of a given year. This rate is like the TFR except that it counts only daughters and literally measures “reproduction”—a woman reproducing herself by having a daughter Contd : Contd Net Reproductive rate:
The net reproduction rate (NRR) is the average number of daughters that would be born to a woman (or group of women) if she passed through her lifetime from birth conforming to the agespecific fertility and mortality rates of a given year. This rate is like the GRR, but it is always lower because it takes into account the fact that some women will die before completing their childbearing years. Replacement level of fertility : Replacement level of fertility Replacement-level fertility is the level of fertility at which women in the same cohort have exactly enough daughters (on average) to “replace” themselves in the population. An NRR of 1.00 is equal to replacement level.
Once replacement-level fertility has been reached, births will gradually reach equilibrium with deaths, and in the absence of immigration and emigration, a population ultimately will stop growing and become stationary. The time this process takes varies greatly depending upon the age structure of the population
The TFR can also be used to indicate replacement-level fertility by showing the average number of children sufficient to replace both parents in the population. In the developed countries today, a TFR of about 2.1 is considered to be replacement-level.
Replacement level TFRs higher than exactly 2.0 (one child for each parent) are needed because there are slightly more males than females born and not all females survive to their childbearing years. In developing countries with much higher mortality rates, TFRs higher than 2.1 are necessary to achieve replacement level Population Momentum : Population Momentum Population momentum refers to the tendency of a population to continue to grow after replacement-level fertility has been achieved. A population that has achieved replacement or below replacement fertility may still continue to grow for some decades because past high fertility leads to a high concentration of people in the youngest ages. Total births continue to exceed total deaths. As these youth become parents. Eventually, however, this large group becomes elderly and deaths increase to equal or outnumber births. Thus it may take two or three generations (50-70 years) before each new birth is offset by a death in the population Exercise : Exercise