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Linear Combination of Two Random Variables. Let X 1 and X 2 be random variables with Let Y = aX 1 + bX 2 . Then,…. Linear Combination of Independent R.V. Let X 1 , X 2 ,…, X n be independent random variables with Let Y = a 1 X 1 + a 2 X 2 + ∙∙∙+ a n X n . Then,….
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Linear Combination of Two Random Variables • Let X1 and X2 be random variables with • Let Y = aX1 + bX2. Then,… week2
Linear Combination of Independent R.V • Let X1, X2,…, Xn be independent random variables with • Let Y = a1X1 + a2X2 + ∙∙∙+ anXn. Then,… week2
Linear Combination of Normal R.V • Let X1, X2,…, Xn be independent normally distributed random variables with • Let Y = a1X1 + a2X2 + ∙∙∙+ anXn. Then,… week2
Examples week2
The Chi Square distribution • If Z ~ N(0,1) then, X = Z2 has a Chi-Square distribution with parameter 1, i.e., • Can proof this using change of variable theorem for univariate random variables. • The moment generating function of X is week2
Important Facts • If , all independent then, • If Z1, Z2,…Zn are i.i.d N(0,1) random variables. Then, week2
Claim • Suppose X1, X2,…Xnare i.i.d normal random variables with mean μ and variance σ2. Then, are independent standard normal variables, where i = 1, 2, …, n and week2
Important facts • Suppose X1, X2,…Xn are i.i.d normal random variables with mean μ and variance σ2. Then, Proof:… • This implies that… • Further, it can be shown that and s2 are independent. week2