# Components of Population Growth Crude Birth Rate (CBR)

Components of Population Growth Crude Birth Rate (CBR) Crude Death Rate

(CDR) Natural Increase Rate (NIR or RNI) Total Fertility Rate (TFR) Infant Mortality Rate (IMR) Crude Birth Rate

Total number of live births in a year for every 1,000 people alive in the society. United States = 13 Niger = 50 Crude Death Rate

Total number of deaths in a year for every 1,000 people alive in a society. U.S. = 9 Niger = 11 Natural Increase Rate (NIR) or Rate of Natural Increase (RNI)

The percentage by which population grows in a year. Compute by subtracting CDR from CBR. Natural means births, this excludes migration. Total Fertility Rate The

average number of children a woman will have in her childbearing years (15-45). Infant Mortality Rate The number of deaths under one year of age occurring among the live births in a given year, per 1,000 live births occurring among the population.

Population Pyramids Key Terms Population Pyramid Dependency Ratio Age Distribution

Sex Ratio Key Terms Defined Population Pyramid: A bar graph representing the distribution of population by age and sex Dependency Ratio: The number of people

under the age of 15 and over age 64 compared to the number of people active in the work force Age Distribution: The percentage of the population within a country in each age group (broken down into 5-year intervals) Sex Ratio: The number of males per 100 females in the population

How it works Males on the left, females on the right Youngest on the bottom (0-4), oldest on the top (100+) Generally done as a percentage

of the population, sometimes as total numbers Shape of the pyramid is generally shaped by the CBR Pyramid for Stage 1 Wide

base = very high birth rate Narrows very quickly = high death rate Very few reach old age Pyramid for Stage 2 Wide

base = High birth rate Wider & taller = people living longer Pyramid for Stage 3 Domed shape = more people living to be older

Proportionately fewer births Pyramid for Stage 4 Small base, small top Bulge in the middle CBR and CDR are low.

Population is stagnant All four Stages Concave Profile Convex Profile

Effects of Population Growth Rapid Growth (stage 2) Slow Growth (stage Need services for children Fewer old people = less money spent on them People move to cities to find work

Countries with the fastest growth have the fastest growing cities Quickly constructed buildings to house workers Often lack vital services (water, electricity,

sanitation) Some migrate to more developed countries 4) Need services for elderly Fewer young people =

less money spent on them Could be shortage of workers in the future Migrants move into the country, often to work in low wage jobs that would be otherwise hard to find workers

http://www.swissinfo.ch/blob/ 42152854/6f002b6af069e92ecbb1bd7a3b3e9f2c/ int-populationstrucutres-en-data.gif Outside Influences Migration: young males are more

likely to migrate Famines: can cause a clear drop in population, especially among the very young War: clear drop in male populations of fighting age Why? We

can gain a lot of information about a city, nation, region, etc. by looking at a population pyramid. Age Lawrence, KS (College town)

Naples, FL (42% over age 65) Gender Unalaska, AK (Military Base)

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