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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  

And that’s it! 

Good luck studying and I’ll see y’all later! 

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