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)
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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 ∈
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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,...
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