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Populations may grow, shrink, or remain stable

▪ Natural rate of population increase=

(Crude birth rate) − (crude death rate)

▪ Population change due to internal factors

▪ Population growth rate=

(Crude birth rate + immigration rate) − (Crude death rate + emigration rate)

▪ Net changes in a population’s size/1000/year

▪ Growth rate as a percent = Population growth rate × 100%

▪ Populations of different sizes can be compared

Crude Birth Rate

• Number of births per 1,000 people in a population in a year.

• The world's population is 8.2 Billion people

• The CBR for the world is 17

• So, through the math, the world is adding 139,400,000 people

• (8,200,000 * 17)

• Formula =(Number of live births / Estimated midyear Population) x 1,000. 

  
  

Crude Death Rate

• The number of deaths in a population per 1000 people in a year.

• Again, the world's population is 8.2

• The CDR is 7.7

• So effectively the world is losing 63,140,000 people per year.

• Formula =(Number of live deaths / Estimated midyear Population) x 1,000. 

Natural Increase Rate

• Crude Birth Rate - Crude Death Rate

• 18.1 - 7.7

• NIR for the world is +10.4 people per 1000 per year.

​Population Growth

​Birthrate and Death rate

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• Growth occurs when birthrate is higher than its death rate

• Equal birth and death rate - zero growth

• Death rate higher than birthrate- decrease in populaiton

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​Population Growth

​Immigration and Emigration

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• Immigration: when individuals move into a population range

• ​Emigration: when individuals move out of a population range

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Population Density

Doubling Time

• The amount of time needed for a population to double based on it's natural increase rate.

• Rule of 70

• formula=70/growth rate as a percent​