Hello!

Thank you so much for reading my case, I hope it´s helpful! I chose this topic because I see many people struggling with market sizings, which are very easy to do whenever you know how to!

What do you mean precisely with usage time?  

There are two ways:

Approach 1: Estimation leveraging # of babies born:

1. Calculate number of babies born every year in the US > 330 M inhabitants / 80 years lifespan = ~4,3M babies.
2. Calculate number of babies per family > Since the average is 2 children/ family, 50% are first child = ~2,1 M babies are 1st born
3. Assume that 90% 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) > ~2,1 stroller
   1. 2,1 M * 0.9 = 1,9 M strollers for first children
   2. 2,1 M * 0.1 = 1,2 M strollers for children who are not first born in the family
4. BONUS: Average price of 200$ = ~$412 M is the total market (*further break down could be done here for purchasing power of families)

Approach 2: Estimation leveraging # of families:

1. Calculate number of families currently in the US > 330 M inhabitants / 3 people per household = ~110 M families
2. Calculate how many households are families with children - assume 80% > ~110 M * 0.8 = 88 M families
3. Calculate how many families buy a stroller - assume 80% > ~88 M * 0.8 = 70.4 M families
4. Calculate how many strollers are bought per year (since we had the total number of strollers existing in the US) - assume 30 years as the time in which a family buys a stroller > 70.4 M families / 30 = 2.3 M strollers bought yearly
5. BONUS: Average price of 200$ = ~$470 M is the total market (*further break down could be done here for purchasing power of families)

Hope it helps!

Cheers, 

Clara

(editiert)