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Birth rate and death rate
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True or false? The death rate is calculated like this: 1000 × [no of people immigrated] / [no of people emigrated]
Oh no! Hope it's nothing serious. Wait! Looks like there's a new citizen on the way! Now that there's one more inhabitant in the town, it's time to update the sign!
There we are! The population has increased. Oh, noo! Now two people died! The population has gone down.
Not again! Let's hope it's another baby! A population consists of all people who live in a country, or in a city. The population amount changes all the time: children are born and people die. To find out how much a population has increased or decreased during one year, we need to keep track of how many have been born: the birth rate... ...
and how many have died -- the death rate. This is China! At the moment it's the most populous country on Earth! In the 1980s the ruling party in China decided that the population had grown too much, too fast. It must decrease!
They decided that each family was only allowed to have one baby. Or else the parents would be punished. The birth rate went down, and has continued to decrease. Now the population grows slowly. This is India.
Here the population increases fast. So fast that India's population will soon be larger than China's! Are more children born than previously? No, actually the birth rate has decreased here too! But the death rate has also decreased.
During recent decades, India has become richer, and the population healthier, reaching a higher age. This has lead to a decreasing death rate. And when the death rate decreases, the population grows. And this is Japan; one of the countries in the world where the population is decreasing. The birth rate is very low, even lower than in China.
And the death rate has started to rise. Wait a minute! Japan is a very rich country! With advanced technologies, robots, and good health care. How can the death rate rise in Japan?
Well, in Japan, for a long time, few babies have been born. A large portion of the population is now made up of old people. And old people, well, they're more likely to die than young ones. So the larger the proportion of old people in a population, the higher the death rate. More people die.
That's why Japan's population is decreasing. So, when we study a population, we need both the birth rate and the death rate. Like this: Here is the approximate size of population, in these three countries. This is how many are born... ... and how many die, each year.
And this is how these numbers change. But if we want to compare, that'll be hard, because the countries are not the same size. So we calculate the figures like this: The number of births and deaths per thousand inhabitants. Now we can compare them. India has the highest birth rate, and the lowest death rate of these three countries.
And Japan has the lowest birth rate and the highest death rate. The population increases the most in India. And in Japan it decreases. But this doesn't give the full picture. The size of the population is affected by two more things.
Care to guess what they are? That's right! We have to count those who migrate as well -- those who move to or from the country, or city. So, there's a lot to keep track of... Hey, that was a whole car full of people, moving in!
Quick, update the sign! But now a whole bus full of people who are leaving went past. Now we're fewer again. The number of births... Minus the number of deaths Plus the number of immigrants Minus the number of emigrants There it is, the change in population!