Exchangeability Probability Interview Questions
Exchangeability probability interview prep for symmetry, random orderings, dependence versus exchangeability, and sampling mistakes.
Advanced candidates using symmetry in random ordering and sampling prompts.
Exchangeability means labels can swap
Exchangeable variables can be relabeled without changing the joint distribution. The positions or labels are symmetric.
Not the same as independence
Independent identically distributed variables are exchangeable, but exchangeable variables do not have to be independent.
Concrete example
A random shuffle makes card positions exchangeable before any card is revealed. Each position has the same role in the shuffled order.
Use in interviews
Exchangeability can justify equal chances for ranks, positions, or selected labels without counting every arrangement.
When it breaks
Conditioning, biased sampling, or different role definitions can break exchangeability. State why labels are still symmetric before using the shortcut.
Common mistakes
Candidates often say variables are independent when they only need symmetry. Use the weaker correct idea when dependence may still exist.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.