PROBLEM 8: It is easy to show with mgf's that the sum of independent chi-squared random...
Solve b 3.6.14. Let Xi, X2, and Xs be three independent chi-square variables with rı, r2, and T3 degrees of freedom, respectively. (a) Show that Yı = X1/X2 and ½ = X1 + X2 are independent and that ½ is x 2) (b) Deduce that and KJr2 (X1+X2)/(n+r2) are independent F-variables. 3.6.14. Let Xi, X2, and Xs be three independent chi-square variables with rı, r2, and T3 degrees of freedom, respectively. (a) Show that Yı = X1/X2 and ½ =...
Practice problems using various statistical methods If n independent random variables X have normal distributions with means μ and the standard deviations σ , then determine the distribution of a. I. X-E(X) var(X) C. 2. If n independent random variables Xi have normal distributions with means μί and the standard deviations σί, then determine the distribution of a. b. Y -a1X1 + a2X2+ + anXn (ai constant) X-E(X) Vvar(X) 3. What is CLT? Proof briefly? What are t-, Chi-squared- and...
Problem 3: Understanding the chi-squared test of independence of categorical random variables The problem has two sub-problems that should help understand the chi-squared test of independence. a) For the chi-squared test of independence between two categorical variables, we use the fact that the MLE for the probability that a multinomial trial is of category i is ni /n, where ni is the number of trials that fall into category i, and n is the total number of trials. Prove the...
21 (1 point) If Y X and every Xi is i.i.d with a chi-squared distribution with 14 degrees of freedom, find the MGF of Y М()- What is the distribution of Y? Select all that apply. There may be more than one correct answer. А. gатта(а - 147, 8 В. датта(а — 2, В — 294) с. датта(а — 1,8— 1/147) D. gamma(a 1, B 1/294) E. chi squared(df 294) F. еzрoпential(A — 204) G. exponential(A 147) H. chi squared(df...
9. Show that Y-Σ|-1 z? has a Chi-squared distribution with n degrees of freedom, where Z's are iid rvs from a standard normal distribution. (Prove it mathematically)
(1 point) In Unit 3, I claimed that the sum of independent, identically distributed exponential random variables is a gamma random variable. Now that we know about moment generating functions, we can prove it. Let X be exponential with mean A 4. The density is 4 a) Find the moment generating function of X, and evaluate at t 3.9 The mgf of a gamma is more tedious to find, so l'll give it to you here. Let W Gamma(n, A...
In this problem we show directly that the sum of independent Poisson random variables is Poisson. Let J and K be independent Poisson random variables with expected values α and respectively. Show that Ņ J+K is a Poisson random variable with expected value α+β Hint: Show that 72 Pk (m)P, (n-m and then simplify the summation be extracting the sum of a binomial PMF over al possible values. In this problem we show directly that the sum of independent Poisson...
7. Let Xn Xi++X2, where the Xi's are iid standard normal random variables (a) Show that Sn is a chi-square random variable with n de- grees of freedom. Hint: Show that X is chi-square with one degree of freedom, and then use Problem 6. (b) Find the pdf of (c) Show that T2 is a Rayleigh random variable. (d) Find the pdf for Ts. The random variable Ts is used to model the speed of molecules in a gas. It...
explan the answer . Suppose that Xi, X2,.... Xn are independent random variables. Assume that E[A]-: μί ald Var(Xi)-σ? where i-| , 2, , n. If ai, aam., an are constants. (i) Write down expression for (i) E{E:-aiX.) and (ii) Var(Σ-lai%). (i) Rewrite the expression if X,'s are not independent.
explan the answer 1l. Suppose that X1, X2,... Xn are independent random variables. Assume that ElXi] /4 and Var(X )-σ, where i 1, 2, . .., n. If ai , aam. , an are constants. 1,a2, , an are constan (i) Write down expression for (i) E{Σ,i ai Xi) and (ii) Var(Li la(Xi). (i) Rewrite the expression if X,'s are not independent.