This is a legacy topic. View the most up to date content by clicking an exam board tab above or visiting the home page.births and deaths. The number of births per 1000 people is called the birth rate, and the number of deaths per 1000 people is the death rate.
The Population Growth RatePopulation growth rate = birth rate - death rate
It's really not a complicated equation, you must admit. Say the birth rate of Switzerland was 23/1000 and the death rate 28/1000. The population growth rate works out as -5/1000 (23/1000 - 28/1000). As a percentage, this is -0.5% growth. This means that there is a net decrease of 5 people per thousand.The Demographic Transition ModelThis is a model used to classify different populations depending on their birth rate, death rate, overall population size, and the factors behind these numbers. There are 5 different stages:
Stage 1Birth rate is
high due to lack of contraception and low education.Death rate is also
high due to poor sanitation, high infant mortality and starvation.Therefore, overall population size remains
low.Stage 2In stage 2, the causes of high death rate ameliorate, but not those behind high birth rate, therefore:
Birth rate is
high for all the reasons in stage 1.Death rate
decreases as more food becomes available and healthcare improves.Overall population size
increases steeply.Stage 3Birth rate
decreases steeply due to contraception availability and family planning.Death rate
decreases more slowly.Overall population size
increases.Stage 4Birth rate is
low due to more money being directed towards assets, and the lack of need for child labour.Death rate is
low.Overall population size is
high and stable.Stage 5Birth rate
decreases as children are expensive to have.Death rate is
stable as many older people die, counteracting the effect of advancing healthcare.Overall population size
decreases for the first time.Life expectancy and Survival RatesLife expectancy graphs refer to the numbers of people who are expected to survive to a certain age.
Here, it can be seen that for 1981 (triangles) 25% conceived survived up to 70 years. In this case, very few people reached 80 years old.
To find out any figure from the graph, just choose a percent first on the
y axis, e.g. 50%, then draw a parallel line to the x axis until it meets the curve. Now draw a line from that crossing point down to the x axis (parallel to the y axis) until it crosses it, and read off the corresponding value (for 1900 it's about 50 years).Age-Population PyramidsThese are special graphs which represent the numbers of males and females in different age brackets. Any significant sex differences can be clearly seen at each age range, as well as the life expectancy of the population, and the proportions of younger to older people.
You can see above that, with time, the proportion of
children in Japan (below 15 years old) decreased from 35.4% to 13.5%. From this data it can be projected (predicted based on past trends) that by 2050 this percentage will drop further to 8.6%.It can also be seen that the percentage of
people aged 65+ increased from 4.9% to 21.5% between 1950 - 2007.Also, in 2007 there can be seen significant numbers of
people aged 90+ appearing, of which most correspond to females.Life expectancy also rose very significantly, with many more people surviving to an older age in 2007 than in 1950. |