Describe how you’d conduct a market sizing exercise for a new product or market segment.

Sizing tests structured reasoning with limited information. The answer matters less than whether your logic is clear and your assumptions are honest.

It scores mainly on analytical rigor and market expertise. On the rubric, a Strong answer on analytical rigor builds arguments from evidence and is explicit about what it does and doesn’t support.

1. Define the market. Who counts as a buyer and what they are buying.
2. Build bottom-up. Number of buyers times likely adoption times price.
3. Cross-check top-down. Compare with a category figure or a similar product.
4. State assumptions and a range. Low, likely, and high cases.
5. Test the weakest input. The one assumption you would verify first.

Treat this as a template for the structure. The facts are invented.

“I define the market first. Say the product is scheduling software for independent dental clinics in the United States. Bottom-up, I estimate the number of independent clinics, then the share that would consider new software, then the price per clinic per year. With about forty thousand clinics, thirty percent open to switching, and an annual price of twelve hundred dollars, the serviceable market is about fourteen million dollars. As a cross-check I would compare it with known spend on practice software in the segment. I would give a range from ten to twenty million dollars and flag that the switching share is my weakest assumption. To test it, I would interview fifteen clinics about what would make them switch.”

“I would look up the size of the industry and take a percentage of it. Then I would use that number to estimate our revenue potential over the next few years.”

The weak answer takes an arbitrary percentage of a large figure. Build the estimate from buyers and price, state the assumptions, and say how you would test the least certain one.

• Which assumption would worry you most?
• How would the number change for enterprise buyers?
• What is the difference between total and serviceable market?
• How would you use the result?

These are the places interviewers press. The follow-up questions guide explains what to say when you reach the edge of your answer.

• A competitive intelligence program
• Win-loss analysis
• Customer wants versus needs
• Building buyer personas
• All market research questions