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Determining the population in each age category?

Anonymous

Hey all, Does this way makes sense to determine the number of people in each catagory?

For example, If the life expectancy in a country is 80 years and the population of the country is 50 million then,

80 / 50 = 0,625 people in each year catagory.

Lets say that I want to know the population segment from 0 to 16 years old. Then

0,625 x 17 = Around 10,6 M people.

Does this makes sense?

What other possible way can we use to determine lets say the population segment from 0 to 16?

Thanks

(edited)

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Andrea
Expert
replied on 06/02/2018
Former BCG decision round interviewer with 300+ real interviews in 8 years

Albeit incorrect - # of people for each age group tends to follow a bell shaped curve - this is a generally accepted way to calculate # of people for each age group.

if you want to be slightly more refine you can say that there are broadly 3 age groups: 0-20,20-60,60-80 and that the middle group should be weighted double for each year it has within it. So you would have that people for each year of age between ages 0-20 and 60-80 is 50M/(20+40*2+20)=0.42M and instead for each year of age between ages 20-60 is 0.42*2=0.84M

hope this helps,

andrea

Francesco replied on 06/02/2018
#1 Expert for coaching sessions (1800+) | Ex BCG | 900+ reviews with 100% recommendation rate

Hi Anonymous,

it’s totally fine to use the approach you presented. As mentioned by Andrea, such computation is clearly an estimate, but it is good enough for market sizing, where you actually suppose to use estimates.

As an additional tip, unless you have specific strict constraints on the different age groups (eg 0-18 as a way to consider people who cannot have a driving licence) it is easier to approximate groups as 15 or 20 years– this will just make faster the computation starting from the initial population.

Best,

Francesco

Vlad replied on 06/02/2018
McKinsey / Accenture / Got all BIG3 offers / More than 300 real MBB cases / Harvard Business School

Hi,

You can either determine the number of people in each category or you can use a % share of each category:

i.e. if you need the population of 10-20, it is 10% of 50M or 5M. It makes sense to predetermine the age groups that you will use in the market sizing questions so that you pick the easy number from the beginning.

Best