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Advanced Probability Theory

Finding the Marginal Distribution of a discrete random variable involves summing over all possible values of the other variable in a joint distribution.

P(X = x) = ∑ P(X = x, Y = y)

In this lesson, we will explore how to marginalize out the variable Y from a joint PMF table. This is a foundational technique for statistical analysis in large datasets.

Step-by-Step Exercise:

  1. Identify the target variable.
  2. Sum the rows (for X) or columns (for Y).
  3. Verify that the total sum equals 1.0.