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STAT 02360 · Probability and Random Variables

STAT 02360 · Random variables

Joint distributions / independence of RVs

Definition

Joint PMF/PDF describes (X,Y) together. Marginals come from summing/integrating out the other variable. Independent RVs: joint factors as product of marginals.

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Covariance and correlation measure linear association; independence ⇒ cov=0 but not conversely.

Conditional distributions: f(y|x)=f(x,y)/f_X(x).

Support matters: restricted triangular regions often create dependence.

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  1. 1.From a joint table, find a marginal and check independence.