Multivariate Probability Distributions in Experiments
Learn about joint, marginal, and conditional distributions of multiple variables to analyze relationships and predict outcomes. Explore multinomial distribution, linear functions, covariance, and regression concepts.
Multivariate Probability Distributions in Experiments
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Presentation Transcript
Multivariate Random Variables • In many settings, we are interested in 2 or more characteristics observed in experiments • Often used to study the relationship among characteristics and the prediction of one based on the other(s) • Three types of distributions: • Joint: Distribution of outcomes across all combinations of variables levels • Marginal: Distribution of outcomes for a single variable • Conditional: Distribution of outcomes for a single variable, given the level(s) of the other variable(s)
Conditional Distributions • Describes the behavior of one variable, given level(s) of other variable(s)
Multinomial Distribution • Extension of Binomial Distribution to experiments where each trial can end in exactly one of k categories • n independent trials • Probability a trial results in category i is pi • Yi is the number of trials resulting in category I • p1+…+pk = 1 • Y1+…+Yk = n
Conditional Expectations When E[Y1|y2] is a function of y2, function is called the regression of Y1 on Y2
Compounding • Some situations in theory and in practice have a model where a parameter is a random variable • Defect Rate (P) varies from day to day, and we count the number of sampled defectives each day (Y) • Pi ~Beta(a,b) Yi |Pi ~Bin(n,Pi) • Numbers of customers arriving at store (A) varies from day to day, and we may measure the total sales (Y) each day • Ai ~ Poisson(l) Yi|Ai ~ Bin(Ai,p)