Quant interview prep guides

Expected Value of Stopping Rules Interview

Expected value of stopping rules interview guide for comparing stop value, continuation value, boundary states, and multi-round decisions.

Candidates practicing optimal stopping and repeated betting variants.

Every state has a stop value

The stop value is what you get by ending the game now. It is the benchmark for deciding whether continuing is worth it.

Continuation value includes future choices

The continuation value is the expected value of taking another step and then following the best allowed policy afterward.

Concrete example

If stopping gives 5 and continuing has expected value 6 before risk constraints, the risk-neutral toy rule continues from that state.

Roll backward when finite

For a fixed horizon, solve the last decision first and move backward. This prevents early choices from being evaluated without future context.

Check boundary states

States like zero bankroll, maximum round, or target reached often have simple values. Use them to anchor the recursion.

Common mistakes

Candidates often compare the next immediate payoff with stopping, but continuation value can include multiple future decisions.

Practice the pattern

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