How do birth, death, fertility, and migration rates affect population size? What factors can affect these rate

Question

How do birth, death, fertility, and migration rates affect population size? What factors can affect these rate

Answer 1

If you compare those rates of countries you can see something like this:

Country  

Average age   Sons         Average    Growth rate   Death rate

JAPAN           per family      age

80's 33.9  

2000 43.3           1.3             81             -0.1%   90's .85%  2000  0.91%

MEXICO  

80's 18.0  

2000 24.1          2.7              70            1.8%   90's .52%  2000 .45%

SOMALIA  

34                       6.1              42              3.2%    12.6%         Somalia's Migration 1.18%

Mexico's migration rate 0.28%

The best way to show, this is Mexican (and Latin) people living in the U.S.

While Americans only have 1 or 2 children, Mexican has 4 (or more)

A decade ago, Mexicans are a little minority in U.S., in twenty years could be a significant part of population, and Mexico keeps its growth rate because a 70% of them comes back after some years to his country

Every rate of that affects the population size. In Somalia where the death rate is high, is compensated by fertility.

In countries like Japan where there are more deaths than births, decrease their population, and its average becomes older.