Transition Matrix Quant Interview Guide
Transition matrix quant interview guide for one-step probabilities, row orientation, matrix powers, Markov chain examples, and mistakes.
Candidates solving finite-state stochastic process prompts.
A transition matrix stores one-step probabilities
A transition matrix lists the probability of moving from each state to each other state in one step. Every row or column should sum to one depending on convention.
State orientation explicitly
Before multiplying, say whether rows represent current states or columns represent current states. Ambiguous orientation causes many otherwise easy mistakes.
Concrete example
If row A has entries 0.7 for staying in A and 0.3 for moving to B, then a process currently in A has those one-step probabilities under the row convention.
Powers give multi-step probabilities
For a time-homogeneous finite chain, squaring the transition matrix gives two-step probabilities under the same orientation convention.
Common mistakes
Candidates often multiply matrices before checking row sums or state order. The lazy reliable move is to label states and orientation first.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.