Lab #5: Fertility

 

We have discussed several different measures of fertility, each of which is more specific in terms of the number of births relative to the population “at risk” of giving birth.  In this lab, you will be using data published by the National Center for Health Statistics of the Center for Disease Control to compute these measures. 

 

Crude Birth Rate

The Crude Birth Rate is the simplest form of describing fertility in a culture, but its primary uses are to compute rates of natural increase and momentum factors.  The CBR does not really tell you much about how many children a typical family has.  It has another inherent weakness.  It uses the entire population as the denominator, thus including all males and all females not in their childbearing years.

 

CBR = #live births/Total Population x 1000

 

General Fertility Rate

The General Fertility Rate begins to control for population structure by computing the number of live births for the population of women in their childbearing years per thousand.  It is similar to the CBR, but the denominator is the at risk population only.

 

GFR = # live births/Population females (15-44)  or = # live births/Population females (10-49) depending on how a country reports its statistics x 1000.

 

Age-Specific Fertility Rate

The Age-Specific Fertility Rate is similar to the age-specific mortality rate in that it measures how many births there are to women in specific age cohorts.  This is a helpful statistic in understanding what the typical childbearing age is in a culture.  The age cohort(s) with the highest rate(s) tell you when childbearing most commonly occurs in a woman’s life in that culture.

 

ASFR = # live births to women in an age cohort/Population of women in that age cohort x1000

 

Total Fertility Rate

The Total Fertility Rate or TFR is the most powerful and useful measure of fertility in understanding a population.  It represents the number of children the typical woman in that population will have over her childbearing years, based on 2 assumptions:

 

  1. Women will have the same birth rates over their lifetimes as women in different age cohorts in that same population have had in that year; and
  2. Women will survive through their childbearing years.

 

TFR = (h S AFSR)/1000

Where h=the number of years in the age cohorts for the ASFR.

 

Using the data below, compute the CBR, GFR, ASFRs and TFR for the US for the year 2001. Present your results in a formal table and submit it in class on Monday 3/17/08. Since I am distributing the midterm on Monday, you do not need to write an essay for this lab.

 
Table 1.  Population, Female Populations by age cohorts, and Live Births by age cohorts, 2001.
  Population Live Births        
Total population 284,796,887 4,025,933        
Females 10-14 10,185,198 7,781        
Females 15-19 9,843,981 445,944        
Females 20-24 9,619,230 1,021,627        
Females 25-29 9,333,209 1,058,265        
Females 30-34 10,260,525 942,697        
Females 35-39 11,138,324 451,723        
Females 40-44 11,477,432 92,813        
Females 45-49 10,544,119 5,083        

 
Source: National Vital Statistics Reports, Vol. 51, No. 4, February 6, 2003, Tables 2, 11.

 

Table 2. Hispanic and Non-Hispanic Female Populations and Number of Live births, 2001
         
  Hispanic Non-Hispanic Hispanic Non-Hispanic
      Live Births Live Births
Total Population 36,972,219 247,824,668 851,851 3,174,082
Females 10-14 1,645,512 8,539,686 2,555 5,226
Females 15-19 1,503,868 8,340,113 130,007 315,937
Females 20-24 1,580,956 8,038,274 258,431 763,196
Females 25-29  1,622,931 7,710,278 227,910 830,355
Females 30-34 1,540,556 8,719,969 150,352 792,345
Females 35-39 1,418,573 9,719,751 67,952 383,771
Females 40-44 1,205,473 10,271,959 13,956 78,857
Females 45-49 958,473 9,585,646 688 4,395

Source: National Vital Statistics Reports, Vol. 51, No. 4, February 6, 2003, Tables 2, 11.