2. Let Zo ~ WN (0, σ ), that is, {A is a sequence of uncorrelated...
7. Let Z be Gaussian white noise, i.e. Z is a sequence of i.i.d. normal r.v.s each with mean zero and variance 1. Define Zt, t(-1- 1)/v2, if t is odd Show that Xis WN(0,1) (that is, variables Xt and Xt+k,k2 1, are uncorrelated with mean zero and variance 1) but that Xt and Xi-i are not i.i.d
7. Let Z be Gaussian white noise, i.e. Z is a sequence of i.i.d. normal r.v.s each with mean zero and variance...
9] 2. Let(X")}, (X12Ί, . . . , { with spectral densities f:i) (w) for-1, 2, . . . , n. Let Xbe n uncorrelated stationary processes Ut i-1 for some constants αι, . . . Prove that Ut is a stationary process. Find the autocovariance function of the process {Ut} in terms of the autocovariance function for each {X)')}, when i - 1,2,... ,k. rove UW) - where fr (w) is the spectral density for the process {Σ¡ι αίΧΙ)}...
P8.4 [Based on exercise 8.2 from Childers, 2nd ed.] Let Wn be an IID sequence of zero-mean Gaussian random variables with variance σ류. Define a discrete-time random process Xn-p Xn-1 + wn, n-1, 2, , where Xo-W) and p is a constant. (a) Find the mean function Hx(n). (b) Find the auto-correlation function Rx(n1,n2).
Let Wt de a (Gaussian) white noise with variance σ 2 . Then, let
Xt = WtWt−1 + µ, where µ is a real constant. Determine the mean and
autocovariance of (Xt)? Is this process stationary?
Let W, de a (Gaussian) white noise with variance σ2. Then, let of where μ is a real constant. Determine the mean and (X)? Is this process stationary?
Let { be a zero-mean stationary process and let a and b be constants. (a) (5 points) If Xi a+bt+St+Yi, where St is a seasonal component with period 12, show that ▽12V is stationary and express its autocovariance function in terms of that of { (b) (5 points) If X1-(a + bt)Sİ + Y. where Sı is a seasonal component with period 12, show that Vi2 is stationary and express its autocovariance function in terms of that of {
3. Let Zt) be a Gaussian white noise, that is, a sequence of i.i.d. normal r.v.s each with mean zero and variance 1. Let Y% (a) Using R generate 300 observations of the Gaussian white noise Z. Plot the series and its acf. (b) Using R, plot 300 observations of the series Y -Z. Plot its acf. c) Analyze graphs from (a) and (b). Can you see a difference between the plots of graphs of time series Z and Y?...
2. Let 'n ,n > l be a sequence of r.v.s such that E[Xi] μί and Var(X) σ for i-: 1, 2, , and Cov(Xi, Χ.j) Ơij for i J. Let {an ,n 1) and (bn, n 1) be the sequences of real numbers. Write down the expressions for i-l (i,Xi, Xi), Cov every i and Ơij 0 for every i j, state Var(Σί ! així), Coy(Σ, aixi, xi),
Let xi, i 1, 2, 3, , be a sequence of nonnegative numbers such that Σ x.-1 and consider the random variable X whose probability function is defined by: x, for x=x1, x2, X3, 0, for all other x What is the variance of X? i= 1
please solve this problems
Consider the following autoregressive processes: W 2W-1X Wo 0 Zn = 3/4 Zq-1 + Xn Zo = 0. (a) Suppose that Xn is a Bernoulli process. What trends do the processes exhibit? (b) Express Wn and Zn in terms of Xn, Xn-1, ..., X1 and then find E[Wn] and E[Zn]. Do these results agree with the trends you expect? (c) Do Wn or Zn have independent increments? stationary increments? (d) Generate 100 outcomes of a Bernoulli...
Suppose that (Wn: n 2 0) is an autoregressive sequence of order 1, so that for n 2 0, where the Z's are i.i.d. and independent of Wo. a) Express Wn as a function of Wo, Z1, , Zn Suppose that |ρ| 〈 1 and var(WD+var(ZI) 〈 OO b) Compute cov(Wm, Wn) for m, n 2 0 c) Prove that there exists a deterministic constant a for which as n -oo and compute a. (Hint: Compute var(Wn)) Suppose, in addition,...