Quant interview prep guides

Fermi Estimation for Research Interviews

Fermi estimation for research interviews, covering model assumptions, uncertainty, sensitivity, sanity checks, and communication.

Research candidates who need assumption-first estimation practice.

Research estimation starts with assumptions

Research interviews may use estimation to test modeling judgment. The assumptions and sensitivity can matter more than the final number.

Discuss uncertainty explicitly

Give a range when inputs are weak and explain which input dominates the answer. This mirrors model-risk thinking in a simple setting.

Concrete example

For a usage estimate, show how the result changes if adoption is 10 percent versus 20 percent. That sensitivity can be the main insight.

Sanity-check scale

Compare the answer with a lower bound, upper bound, or familiar benchmark. Research-style reasoning should not accept impossible scales.

Common mistakes

Candidates often hide uncertainty to sound confident. Research estimation rewards transparent uncertainty and good checks.

Practice the pattern

Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.