Market Sizing: Strollers

Edited on Mar 04, 2020
5 Answers
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Thomas asked on Jan 28, 2019

During an interview, I received the questions to estimate the market of strollers in the US.

I structured as follows:

1. Number of babies born every year as 300M inhabitants / 80 years lifespan x 1% growth = 3,8M

2. On average 2 children so 50% are first child and 50% are second, third... child

3. I assumed that 80% of first children receive a new stroller while only 10% of second, third children receive a new stroller (90% inherit the stroller from the previous child) resulting in 1,7M strollers a year

4. Average price of 200$ so total market of 340M$

Does this sound like a good approach to you as unfortunately I didn't receive an offer to come back and I wanted to know if it might have had to do with my solution to the case.


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Content Creator
replied on Jan 28, 2019
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


I agree with your initial approach and don't agree with Luca. Basically, you are making a reasonable assumption about the Birth Rate. If you apply growth - just make sure that the population is growing (although the number is small anyway)


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replied on Jan 28, 2019
Bain and BCG experience - Industry hire experience - 150+ cases

Hi Thomas,

the most important thing to do during a market sizing is to make reasonable hypotesis, easy steps and detail the steps as much as you can (make them deep) while maintaining an overall execution time within 10/20 mins max.

Said this, looking at your approach I find that your first assumption may be a bit hursh... you are basically saying that all the population in 1 yr bucket will have a child every year... so like saying people within 34 and 35 will have a child... All of them will have a child and nobody else will have. Unless I misunderstood your calculation

Maybe the number is also correct (idk), but for sure the hypotesis is not clear to me... I would have procced dividing the population into buckets (10 years span per bucket) and then defining some drivers as: Children yes/no (for example below 15 and over 70 I sould say no), then Likelyhood ( from 20 to 30 maybe 20%, from 30 to 40 maybe 30%, from 40 to 50 maybe 20% ...) thenyou can add your filter (1st/ 2nd child)... and so on

But I would have been much more granular while making the hypotesis and explaining them to the interviewer. Remember the number is important, but is nothing without a clear, reasonbable and understandable explanation

Hope this can help

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Klaus on Jan 29, 2019

I don't think that you interpret this calculation correctly. I guess with population/ avg lifespan you calculate how many people are in a "1 year lifespan bucket" assuming a unform distrubution. Thus it is okay in my opinion to say that there is one new "1 year bucket" every year which - in other words - must be the number of new babies born.

updated an answer on Jan 29, 2019
McKinsey Senior EM & BCG Consultant | Interviewer at McK & BCG for 7 years | Coached 300+ candidates secure MBB offers

I like your approach! It is pragmatic, easy to follow, and allows for a clear discussion of the different underlying drivers.

Cheers, Sidi


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Content Creator
updated an answer on Mar 04, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut



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replied on Feb 05, 2019
Interview received from MBB, actively preparing, 40+ mock experience

Somethings to be considered, just sharing, thanks:

1. should be strollers for new babies, and for existing babies' replacement (can add this at the end with a %)

2. % use strollers, % not use

3. 1st baby can buy new & second hand, 2nd baby can also buy new & second hand

4. the babies are from low income, middle income and rich families, so the average price can be segmented further

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Eva on Feb 05, 2019



Vlad gave the best answer


Content Creator
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School
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