b) Consider the I(1) process DeltaYt : m + et, where
et ~ WN(0, sigma^2).
Take now the first difference of DeltaYt. What, kind of process do
you obtain? Is it stationary? Is it invertible? Discuss.
b) Consider the I(1) process DeltaYt : m + et, where et ~ WN(0, sigma^2). Take...
Consider y, = у,-1-0.25%-2 + et-1.54-1 + 0.54-2, et ~ WN(0, σ2). a) Determine the order of this ARIMA model b) Determine if this process is stationary, causal, and invertible.
Consider y, = у,-1-0.25%-2 + et-1.54-1 + 0.54-2, et ~ WN(0, σ2). a) Determine the order of this ARIMA model b) Determine if this process is stationary, causal, and invertible.
Consider the process where B is a backwards shift operator so that BXt-Xt-i and the {Zt) are assumed to be independent random errors. (a) [2 marks] Identify what kind of nonseasonal ARIMA(p,d,q) process this is; that is give the parameters (p,d,q) and give the abbreviated name for this particular process. (b) [3 marks] (i) Is this particular process stationary? Explain. (ii) Is this process invertible? Why?
Consider the process where B is a backwards shift operator so that BXt-Xt-i and...
2. Consider an ARMA(1,1) process, X4 = 0.5X:-1 +0+ - 0.25a4-1, where az is white noise with zero mean and unit variance. (a) Is the model stationary? Explain your answer briefly. (b) Is the model invertible? Explain your answer briefly. (c) Find the infinite moving-average representation of Xt. Namely, find b; such that X =< 0;&–; j=0 (d) Evaluate the first three lags of the ACF and PACF.
2. Consider a following time series process Yt = 1.5Yt−1 −0.5Yt−2 +εt a) Rewrite this process in lag polynomial form. b) Is this process invertible? Is this process covariance stationary? c) Difference this process once and show that ΔYt = Yt −Yt−1 is covariance stationary.
Consider the process Y.-μ + et-o, et-1-912 et-12, where {ed denotes a white-noise process with mean 0 and variance σ? > 0. Assume that et ls independent of Yt-1, Yt-2, Find the autocorrelation function for (Yt).
b) In what follows, we assume cc return r_t is a covariance stationary process. Prove the following statements: i. If r_t iid(0; sigma^2) (or independent white noise); then r_t mds(0; sigma^2). ii. If r_t mds(0; sigma^2); then r_t WN(0; sigma^2) (or weak white noise).
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,...
6. (13 marks) where {U, } ~ WN(0,00) is Consider two independent AR(1) series< independent of {K} ~ WN(0,OF). Does their sum Z,-X,-X necessarily follow an AR(1) series? Prove or disprove. (Hint: Compare the causal representation of the sum to that of an AR(1) process)
6. (13 marks) where {U, } ~ WN(0,00) is Consider two independent AR(1) series
QUESTION 3 (a) Consider the ARMA (1, 1) process -Bat-1-where o and θ are model parame- are independent and identically distributed random variables with mean 0 z, oz,-1 ters, and a1, a2, and variance σ (i) Show that the variance of the process is γ,- (ii) Using (i) or otherwise, show that the autocorrelation function (ACF) of the process is: ifk=0. (b) Let Y be an AR(2) process of the special form Y-2Y-2e (i) Find the range of values of...