Hi,

I would suggest that you should present your own approach and I would be happy to review.

Meanwhile please see below my approach to segmentation in market sizing as well as examples of solved cases:

B2C:
-Demographics (Age, education, income, family size, race, gender, occupation, nationality)
-Behavioral (Purchasing behavior, customer journey stage, occasion & timing,
customer loyalty & interest, risk tolerance, user status)
-Psychographic (Lifestyle, personality traits, values, opinions, interests of consumers)
-Geographic (Geographical boundaries)

B2B:
-Company characteristics (Industry, company size, number of employees)
-Geography (Geographical boundaries)
-Purchasing Approach (Occasion & timing, customer capabilities, nature of existing relationship)
-Personal Characteristics (Loyalty, risk attitude, user status)

B2G:
-Demographics (Type of agency, size of budget, the amount of autonomy)
-Geographic (Geographical boundaries)
-Government Tier (Federal , State, Local, Quasi-governmental, International)
-Bid type (Closed, Open)

But sometimes you don’t need to segmentation. Here is an example of case that could be solved with high level top down approach - estimate the size of credit card market in the US:
https://www.preplounge.com/en/consulting-forum/how-should-i-approach-the-following-question-estimate-the-market-size-of-credit-cards-in-the-us-6695

Hi there,

I would split the question into 3 sub-questions:

1) How many people pass by the airport per month = number of runways * flights per month per runway * average occupancy of a plane --> you get the airport footfall

2) What is the percentage of those travellers who would need to withdraw cash? (you could split the foot traffic by age group and apply a % per age group) --> you get the number of monthly ATM transactions

3) How many monthly transactions is needed to make an ATM profitable? (you can ask the interviewer or you could assume around 50) --> divide the number of you get from step 2 by this rate and you will get the numbers of ATM in the airport

What do you think? How did you approach this question?

I hope this helps,

Khaled