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I sometimes get stuck at the first step because I cannot tell whether to size from total population, households, or some other unit. Is there a general rule for choosing the base, or does it depend entirely on what is being bought?
Mayank G.Coach19 minutes agoEx-BCG | 100% improvement guarantee or you don't pay! | Top 1% Coach!
Use the unit that best matches how the product is purchased or consumed.
The right base reduces unnecessary assumptions and conversions.
Home internet is naturally household-based, while personal insurance is usually individual-based.
Before calculating, identify who actually makes the purchase and use that as the base.
In a market-sizing case, the interviewer gave me a population figure that did not match what I thought was correct. I froze because I did not know whether it was a test or just a simplified assumption. Should you challenge a number the interviewer gives you if you think it is wrong?
Mayank G.CoachUse the number provided for the case unless there is a clear reason to clarify what it represents.
In one practice market sizing case, changing a single penetration assumption moved the answer by almost 2x. I was not sure whether that meant my structure was bad or whether I was supposed to call out how sensitive the estimate was. How should you handle that during an interview?
Mayank G.CoachCall out the sensitivity. A market-sizing estimate can still be useful even when one assumption has a large effect, as long as you recognize which assumption is driving the range.
I had a market sizing in an interview and the structure itself was okay, but once I got into assumptions I felt lost. I kept second-guessing whether the numbers were reasonable, which made the whole thing much slower than it should have been. How do people get better at making assumptions confidently without sounding like they are just making things up?
Mayank G.CoachThe key is to remember that assumptions are not judged on exact precision. They are judged on whether they are reasonable, transparent, and internally consistent.