1. Population Calculations Data from: Population Reference Bureau. 2003 World Population Data Sheet. Available at http://www.prb.org/pdf/WorldPopulationDS03_Eng.pdf. http://www.prb.org/pdf/WorldPopulationDS03_Eng.pdf

2. Population Estimates World population—6,314,000,000 (rounded) Population percentages Most populous country—China (1,288,700,000) China has (1,288,700,000/6,314,000,000) x (100) = 20.4% of the world’s people India is next (1,068,600,0000) India has (1,068,600,000/6,314,000,000) x (100) = 16.9% of the world’s people China and India contain 37.3% (20.4% + 16.9%) of the world’s people

3. Natural Increase (%) This parameter helps project future population. Natural increase (%) = [birth rate/1000 – death rate/1000] x [100] The world has a natural increase of about 1.3% More developed countries—0.1% Less developed countries—1.6%

4. Population Doubling Time Number of years for a population to double in size, assuming rate of population growth unchanged Doubling time = 70/ Natural Increase (%) World = 70/1.3 = 53.9 In a century, the world will have approximately 2 doublings 2 doublings = 2 2 = 4x as many people

5. Infant Mortality Rate Infant mortality rate—number of deaths to infants (children under 1 year of age) per 1,000 live births Worldwide, 55 out of 1000 (5.5%) babies do not survive the first year Many countries have rates well over 100 infant deaths per 1000 live births There is a large difference in infant mortality rates between more developed and less developed continents

6. GNI PPP per Capita GNI PPP per capita is Gross National Income in Purchasing Power Parity divided by midyear populations. From the population data sheet ($US): United States--$34,280 Europe--$16,270 South America--$6,910 Asia--$4290 Africa--$2120

7. Population Productivity Generally, the productivity of a person remains at its peak between the ages of 15 and 65. That means that countries with higher proportions of their populations in this age range have the potential to be more productive than a population with more children or elderly. Age dependency ratio = (% under 15 + % 65+)/(% 15-65) Age dependency ratio (USA) = (21+13)/(100-34) = 0.5 Age dependency ratio (Africa) = (42+3)/100-45) = 0.8 Age dependency ratio (Niger) = (50+2)/(100-52) = 1.1

8. Life Expectancy at Birth Life expectancy at birth is the average number of years a newborn infant can expect to live under current mortality levels. A baby born in 2003 can expect to live, on average, 69 years (female) or 65 years (male). The value for females varies from 85 years for Japan to 40 years for Zimbabwe, a range of 45 years (85-40). This is an indication of the wide differences in conditions in various countries.

9. Summarizing Data: Means The mean is an average. Mean (simple average) = sum of data values/observations Example: In Northern Africa infant mortality rates are given per 1000 people for each of the 7 countries: 54, 44, 30, 37, 70, 23, 134 Sum of data values = 392 Number of observations = 7 (countries) Average infant mortality rate = 56/1000

10. Summarizing Data: Range & Median Range = Maximum - Minimum Infant mortality rate range = 134 - 23 = 111 Median = data value below and above which we have 50% of the data values Sort the data: 23, 30, 37, 44, 54, 70, 134 The 4th observation is the data value below and above which we have the same number of observations; hence, 44 is the median. Median infant mortality rate is 44/1000, which is lower than the mean. How is the median different from the mean?

11. Population Projections Population projection is difficult. There are many factors that contribute towards population projection, such as Birth rate Death rate Political stability of the country Natural disasters, etc. Taking care of all such variables, one tries to fit a model to the existing data. This is called statistical modeling.