a) Prove that if Y is a random variable with all of its cumulants of order greater than two equal to zero, i.e., 0 = K_3 = K_4 = ......... then Y has a normal distribution.
b) Suppose that Z has cumulant generating function k_Z(t) with E(Z) = 0 and Var(Z) = 1. Let Y = σZ + μ. Find the cumulant generating function of Y , k_Y (t) in terms of k_Z(.). Use this to prove that all cumulants except K_1 are location invariant, i.e. do not depend on μ.
a) Prove that if Y is a random variable with all of its cumulants of order...
Let at XW) =andom variable. Prove III. VARIANCE PROOFS (SINGLE RANDOM VARIABLE) Let S be a sample space. Let a, b, c be real numbers. a) Let X(W) = c for all w ES. Prove that Var(X) = 0. b) Let Y be a random variable. Prove that Var(Y + b) = Var(Y). c) Let Z be a random variable. Prove that Var(az) = a-Var(Z). d) Let W be a random variable. Use parts (b)-(c) to prove that Var(aW+b) =...
Question 4. [5 marksi Let Xbe a random variable with probability mass function (pmf) A-p for -1, 2,... and zero elsewhere (whereq-1-p, 0 <p< (a) Find the moment generating function (mg ofX. C11 (b) Using the result in (a) or otherwise find the expected value and variance of X. C23 (c) Let X, X,., X, be independent random variables all with the pmf fix) above, and let Find the mgf and the cumulant generating function of Y.
(a) If var[X o2 for each Xi (i = 1,... ,n), find the variance of X = ( Xi)/n. (b) Let the continuous random variable Y have the moment generating function My (t) i. Show that the moment generating function of Z = aY b is e*My(at) for non-zero constants a and b ii. Use the result to write down the moment generating function of W 1- 2X if X Gamma(a, B) (a) If var[X o2 for each Xi (i...
please explain all steps value when p= p= p= 1, and p = h. Note that the kurtosis increases as p decreases. 1.9.17. Let y(t) = log M(t), where M(t) is the mgf of a distribution. Prove that V'(0) = pi and "(0) = 02. The function f(t) is called the cumulant generating function.
Problems binomial random variable has the moment generating function ψ(t)-E( ur,+1-P)". Show, that EIX) np and Var(X)-np(1-P) using that EXI-v(0) and Elr_ 2. Lex X be uniformly distributed over (a b). Show that EX]- and Varm-ftT using the first and second moments of this random variable where the pdf of X is () Note that the nth i of a continuous random variable is defined as E (X%二z"f(z)dz. (z-p?expl- ]dr. ơ, Hint./ udv-w-frdu and r.e-//agu-VE. 3. Show that 4 The...
X and Y are random variables (a) Show that E(X)=E(B(X|Y)). (b) If P((X x, Y ) P((X x})P({Y y)) then show that E(XY) = E(X)E(Y), i.e. if two random variables are independent, then show that they are uncorrelated. Is the reverse true? Prove or disprove (c) The moment generating function of a random variable Z is defined as ΨΖφ : Eez) Now if X and Y are independent random variables then show that Also, if ΨΧ(t)-(λ- (d) Show the conditional...
problems binomial random, veriable has the moment generating function, y(t)=E eux 1. A nd+ 1-p)n. Show that EIX|-np and Var(X) np(1-p) using that EIX)-v(0) nd E.X2 =ψ (0). 2. Lex X be uniformly distributed over (a b). Show that ElXI 쌓 and Var(X) = (b and second moments of this random variable where the pdf of X is (x)N of a continuous randonn variable is defined as E[X"-广.nf(z)dz. )a using the first Note that the nth moment 3. Show that...
P6.5 [Based on P9.2.4 from text] Let X be a Gaussian(0,02) random variable, i.e. it has zero mean and σ2 variance. Use the moment generating function to show that Let Y be a Gaussian(μ, σ*) random variable. Use the moments of X to show that
Q. 5. Let X be any random variable, with moment generating function M(S) = E[es], and assume M(s) < o for all s E R. The cumulant generating function of X is defined as A(s) = log Ele**] = log M(s), SER Show the following identities: (1) A'(0) = E[X]. (2) A”(0) = Var(X). (3) A"(0) = E[(X - E[X]))). Using the inversion theorem for MGFs, argue the following: (4) If A'(s) = 0 for all s ER, then P(X=...
Let X, Y and Z be three independent Poisson random variable with parameters λι, λ2, and λ3, respectively. For y 0,1,2,t, calculate P(Y yX+Y+Z-t) (Hint: Determine first the probability distribution of T -X +Y + Z using the moment generating function method. Moment generating function for Poisson random variable is given in earlier lecture notes) Let X, Y and Z be three independent Poisson random variable with parameters λι, λ2, and λ3, respectively. For y 0,1,2,t, calculate P(Y yX+Y+Z-t) (Hint:...