60-second structures and fast sizing
A minute-by-minute method for structuring, three example trees, and a three-line sizing method.
Key takeaways
- A fast structure is not a rushed one. It follows the logic of the decision, has three or four buckets that do not overlap, and marks where you would start.
- Where fast sizing goes wrong: Too many steps (each one adds error and time).
- Seconds 0 to 10: restate the objective and the measure of success.
- Seconds 10 to 30: pick three or four top buckets from the logic of the decision (is it attractive, can we win, what does it cost, what could go wrong), not from a memorized list.
- Seconds 30 to 50: add two or three branches under the bucket you think matters most.
This is part of the expert track. It assumes you have worked through the foundation lessons (structuring, case math, exhibits, synthesis) and several case types, and that you have run a few cases out loud. If not, start there and come back.
Key idea
A fast structure is not a rushed one. It follows the logic of the decision, has three or four buckets that do not overlap, and marks where you would start.
Many interviewers let you take a minute or two to structure; some expect you to start talking sooner. Practicing a 60-second version means you are never the candidate who takes four minutes and still has a list instead of a structure.
The 60-second structure
- 1Seconds 0 to 10: restate the objective and the measure of success. "The goal is to decide whether the center would earn at least its cost of capital within five years."
- 2Seconds 10 to 30: pick three or four top buckets from the logic of the decision (is it attractive, can we win, what does it cost, what could go wrong), not from a memorized list.
- 3Seconds 30 to 50: add two or three branches under the bucket you think matters most. That is your hypothesis made visible.
- 4Seconds 50 to 60: say where you would start and why. "I would start with demand, because without enough procedures nothing else matters."
- Open a day-surgery center?
- Key: Demand
- Procedures that can move from inpatient to day surgery
- Referrals from our own clinics and doctors
- Insurer rules on where procedures are paid
- Economics
- Revenue per procedure and payer mix
- Build cost and staffing
- Break-even volume
- Ability to win
- Surgeons willing to operate there
- Rival centers nearby
- Risks
- Licensing time
- Taking patients from our own hospital beds
Built in about a minute. The most likely deciding bucket (demand) gets the most branches.
- Why are approvals slow?
- What comes in
- Volume and its peaks
- Share of applications that arrive incomplete
- Key: The process steps
- Checking documents
- Property valuation
- Credit decision and sign-off
- Capacity
- Staff per step
- Rules that force manual review
- Hand-offs and waiting
- Queues between teams
- Waiting for the customer
An operations question, so the buckets follow the flow of work: what comes in, how it moves, and what limits it.
- How to respond to the rival?
- The move
- Which customers and regions it targets
- Whether its price is sustainable
- Key: Our exposure
- Volume at risk by brand and region
- Profit at risk
- Our options
- Match price
- Launch a lower-price second brand
- Hold price and add value
- Deals with retailers
- The rival's next move
- How it would react to each option
A competitive response: understand the move before choosing the reply, and think one move ahead.
Fast market sizing
Three lines, then a check
- Choose the unit that buys: people, households, businesses, or vehicles. Pick the one closest to the purchase.
- Filter to who buys, then how often and how much. Round each input to an easy number and say that you are rounding.
- Multiply in one line, keep the zeros in short form (million, billion), and give the answer with its unit and period.
- Sense check against something you know: a share of the economy, a number of stores, or spending per person. Give a range only once, at the end, if the interviewer asks for it.
Too many steps (each one adds error and time). Mixing people and households in the same line. Forgetting the period: "per year" or "per day". Rounding every input in the same direction, which pushes the answer far from the truth. The full method is in the Market sizing and estimation module; this section is about doing it in two minutes.
Practice
Start a 60-second timer. Prompt: "A South African grocery chain wants to launch home delivery in Johannesburg. Should it?" Build and say your structure out loud before the timer ends, then compare with the model.
Size UK school uniform spending fast. Assume 10 million pupils, 90 percent attend schools with a uniform, and each of those spends GBP 200 a year on uniform. What is the market, in GBP millions a year?
Size annual helmet spending in Mumbai. Assume 21 million people, 4.2 people per household, 40 percent of households own a two-wheeler, 2 helmets per two-wheeler, replaced every 3 years, at INR 1,500 each. Answer in INR crore a year (1 crore is 10 million).
Size daily coffee cups sold in Singapore. Assume about 6 million people, half drink coffee, and coffee drinkers have 1.5 cups a day. How many cups a day, in millions?
What should the first 10 seconds of a 60-second structure contain?
Where should most of the branches in a fast structure go?
In a fast sizing, when should you give a range?
Sources for this lesson (1)
- Recognized public explanations of case-interview concepts and frameworks
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