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## There Are Eight of ‘em!

In AP Human Geography (AP HuG), there are eight basic population statistics you should know for the exam!

- The crude birth rate (CBR/birth rate)
- The crude death rate/mortality rate (CDR/death rate)
- The rate of natural increase (RNI)
- Doubling time
- The net migration rate
- The total fertility rate
- The dependency ratio
- The demographic equation

Once you have these down, you will be good to go!

## So let’s get into it! 🕺

## The Crude Birth Rate 👶

- The crude birth rate (CBR/birth rate) is an annual statistic.
- This statistic measures the rate of live births in a country’s population every year.
- The higher the CBR, the more humans are being added to the total population. The lower, the less. It is indicative of a country’s level of development or current situation.
- The formula to determine the CBR is: CBR = (# of live births/total population) x 1,000

## The Crude Death Rate ☠

- The crude death rate/mortality rate (CDR/death rate) is also an annual statistic, like the CBR.
- This statistic measures the rate of deaths in a country’s population every year.
- The higher the CDR, the more humans are being taken from the total population. The lower, the less, similarly to the CBR.
- The formula for the CDR goes like this: CDR = (# of deaths/total population) x 1,000

## The Rate of Natural Increase 📈📉

- The rate of natural increase (RNI) is also an annual statistic which estimates the percentage of population growth of a country for each year.
- To find the RNI, you’ll need the CBR and CDR and here’s the formula: RNI = (CBR - CDR)/10
- Additionally, it is also possible to have a negative RNI, as the rate of deaths can outnumber the rate of live births in a country, especially for the highly developed ones.
- For instance, Russia is undergoing a population decline, as seen with its own negative RNI, which is due to a large elderly population and fewer number of women wanting to have children in Russia.
- The RNI is also indicative of a country’s development and current population situation.
- However, it does NOT take into account immigration/emigration. Thus, the RNI doesn't accurately predict population growth, so it is only an estimate.

## Doubling Time ⏭

- The doubling time is a pretty simple statistic and is in partner with RNI.
- Doubling time looks at how long a country will take to double its population with its given RNI.
- The formula for doubling time looks like this: Doubling Time = (70)/RNI
- However, this statistic is also an estimate since it only predicts a time period based on the given RNI, which does not take into account total migration.

## The Net Migration Rate 🚪

- The net migration rate (NMR) is also an annual statistic that measures the rate at which people are leaving and entering the country.
- It looks at the number of people entering (immigrants) and leaving (emigrants) to see which group is larger or if both groups are equally balanced.
- It’s also possible to have negative, positive, or even zero NMR.
- The NMR also gives a quick glance into what the country is/is not offering to people to make them come/leave. Basically, it helps us quickly see if either the push (to leave) or pull (to come) factors are stronger in a country.
- Formula for the net migration rate: NMR = (# of immigrants = # of emigrants)/(population + 1,000)

## The Total Fertility Rate 🤰

- The total fertility rate is a statistic that measures the average number of children an average woman of child-bearing age would have at a certain age.
- However, if you noticed, I did not mention this rate is an annual statistic.
- The TFR is actually more of a statistic that takes a snapshot of a country’s fertility within a time period of 30 years.
- The TFR also helps us take a quick peek into the size of a country’s youth group and the number of people being naturally added to the total population.
- The total fertility rate’s formula follows as so -
- TFR = (# of children born)women aged 15 to 45

## The Dependency Ratio 👴👶:👨👩

- The dependency ratio is more so a ratio than a number with a formula to use.
- What the dependency ratio looks at is comparing the number of people unable to work (dependents) to the number of people of working ages.
- This allows us to look at a country and determine the burden of the workforce to help provide for the rest of society and where the country lies in terms of demographic, economic development, and more.

## The Demographic Equation 📊

- As you could guess from the name, the demographic equation is a formula that will help us determine which Demographic Transition Model (DTM) stage a particular country would belong in.
- In other words, it helps us look at a country’s population demographics and give a more accurate population growth projection.
- This formula takes into account the CBR, CDR, and NMR to determine a more precisely predicted population growth percentage rate.
- Demographic equation: Population growth percentage rate = ((CBR - CDR) + NMR)/10