1. Suppose X1, ..., Xn be a random sample from Exp(1) and Y1 < ... < Yn be the order statistics from this sample.
a) Find the joint pdf of (Y1, .. , Yn).
b) Find the joint pdf of (W1, .. , Wn) where W1 = nY1, W2 = (n-1)(Y2 -Y1), W3 = (n - 2)(Y3 - Y2),..., Wn-1 = 2(Yn-1 - Yn-2), Wn = Yn - Yn-1.
(c) Show that Wi's are independent and its distribution is
identically Exp(1).
(d) Show that nY1 and sum(Xi-Y1)
are independent.
(e) Show that sum(Xi-Y1) ~ Gamma(n - 1,
1).
(f) Using (b) and (c), compute E(Y3).
1. Suppose X1, ..., Xn be a random sample from Exp(1) and Y1 < ... <...
Let X1, X2, ..., Xn be independent Exp(2) distributed random vari- ables, and set Y1 = X(1), and Yk = X(k) – X(k-1), 2<k<n. Find the joint pdf of Yı,Y2, ...,Yn. Hint: Note that (Y1,Y2, ...,Yn) = g(X(1), X(2), ..., X(n)), where g is invertible and differentiable. Use the change of variable formula to derive the joint pdf of Y1, Y2, ...,Yn.
Let Y1<Y2<...<Yn be the
order statistics of a random sample of size n from the distribution
having p.d.f f(x) = e-y , 0<y<, zero elsewhere. Answer the following
questions.
(a) decide whether Z1 = Y2
and Z2=Y4-Y2 are
stochastically independent or not. (hint. first find the joint
p.d.f. of Y2 and Y4)
(b) show that
Z1 = nY1, Z2=
(n-1)(Y2-Y1),
Z3=(n-2)(Y3-Y2), ....,
Zn=Yn-Yn-1
are stocahstically
independent and that each Zi has the exponential
distribution.(hint use change of variable technique)
Let X1, ..., Xn be a random sample from Gamma(1,41) distribution and Y1, ..., Ym be a random sample from Gamma(1,12) distribution. Also assume that X’s are independent of Y's. (1) Formulate the LRT for testing Ho : 11 = 12 v.s. Hy : 11 + 12; (10 points) (2) Show that the test in part (1) can be based on the following statistic (7 points) T = 21-1 Xi Dizi Xi + [2Y; = (3) Find the distribution of...
Suppose that X1, X2,.... Xn and Y1, Y2,.... Yn are independent random samples from populations with the same mean μ and variances σ., and σ2, respectively. That is, x, ~N(μ, σ ) y, ~ N(μ, σ ) 2X + 3Y Show that is a consistent estimator of μ.
The training data consists of N pairs (x1,y1),(x2,y2),··· ,(xN,yN), with xi ∈
Let X1, ..., Xn be a random sample from a population with pdf f(x 1/8,0 < x < θ, zero elsewhere. Let Yi < < Y, be the order statistics. Show that Y/Yn and Yn are independent random variables
Let X1,X2,...,Xn be an independent and identically distributed (i.i.d.) random sample of Beta distribution with parameters α = 2 and β = 1, i.e., with probability density function fX(x) = 2x for x ∈ (0,1). Find the probability density function of the first and last order statistics Y1 and Yn.
8. Let X1,...,Xn denote a random sample of size n from an exponential distribution with density function given by, 1 -x/0 -e fx(x) MSE(1). Hint: What is the (a) Show that distribution of Y/1)? nY1 is an unbiased estimator for 0 and find (b) Show that 02 = Yn is an unbiased estimator for 0 and find MSE(O2). (c) Find the efficiency of 01 relative to 02. Which estimate is "better" (i.e. more efficient)?
8. Let X1,...,Xn denote a random...
Let X1~ exp(1) and X2 ~ exp(1) be independent and identically-distributed exponential random variables with rate 1. Let: Y = X1 + X2 , Z = X1 − X2 (a) What is the cdf of X1? (b) What is the joint pdf of (X1, X2)? (c) What is the joint pdf of (Y, Z)? (d) What is the marginal pdf of Z?
We will need this important result of this problem for something that is coming up in class! Suppose that X1, X2, ..., Xn 10 N(4, 02). (a) Show that 2-1(Xi – u)2 -1(X; – X) n(X – u)2 02 o2 T 02 (This has nothing to do with the particular distribution here.) (b) Write down the joint pdf for X1, X2, ..., Xn and use the above to rewrite the "e-exponent part”. (c) Consider the joint transformation Y1 = X,...