: Assume Yt is a time series process and Et is a white noise process with mean zero and constant variance.
(a). Write an equation for AR(4) process.
(b). Write an equation for AR(5) process.
(c). Write an equation for MA(3) process.
(d). Write down an equation for MA(2) process.
(e). Write an equation for ARMA (4,2) process.
(f). Do more research and write an equation for ARIMA (4,0,2) proce
: Assume Yt is a time series process and Et is a white noise process with...
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).
(A). Draw the Autocorrelaogram and Partial Autocorrelogram for a White Noise Time Series Process. (B). Assume that the optimal h-steps ahead forecast is noted as fth for a MA(1). Lets also assume that the optimal point forecast is a conditional expectation: Where Qt is the information set at time "t" and "h" is the forecast horizon. Now we can write the MA(1) process at time "t+1" as follows; Ü. What is the optimal one period ahead forecast, f,i? (ii). What...
Let {et} denote a white noise process from a normal distribution with E[et] = 0, Var(et) = σe2 and Cov(et, es) = 0 for t ≠ s. Define a new time series {Yt} by Yt = et + 0.6 et -- 1 – 0.4 et – 2 + 0.2 et – 3. 1. Find E(Yt ) and Var(Yt ). 2. Find Cov(Yt , Yt – k) for k = 1, 2, ...
2. Let (et) be a zero mean white noise process with variance 1. Suppose that the observed process is h ft + Xt where β is an unknown constant, and Xt-et- Explain why {X.) is stationary. Find its mean function μχ and autocorrelation function p for lk0,1,.. a. b. Show that {Yt3 is not stationary. C. Explain why w. = ▽h = h-K-1 is stationary. d. Calculate Var(Yt) Vt and Var(W) Vt . (Recall: Var(X+c)-Var(X) when c is a constant.)...
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2. Let [et be a zero mean white noise process with variance 0.25. Suppose that the observed process is k = et + 0.5e-2. a. Explain why {Yt) is stationary. b. Compute yo-V(Y.) c. Compute the autocorrelation pkY, kl-0,1,2,... for Y) d. Let Wt = 3 + 4t + h. i. Find the mean of {W) ii. Is W3 stationary? Why or why not? iii. Let Z Vw, W,- W,_1. Is {Z.1 stationary? Why or why not?
4. Calculate the variance of the time series rt (i.e. Var(rt)) for the following ARMA(1,1) model: where the variance of the white noise series is 0.09. 4. Calculate the variance of the time series rt (i.e. Var(rt)) for the following ARMA(1,1) model: where the variance of the white noise series is 0.09.
QUESTION4 (a) Let e be a zero-mean, unit-variance white noise process. Consider a process that begins at time t = 0 and is defined recursively as follows. Let Y0 = ceo and Y1-CgY0-ei. Then let Y,-φ1Yt-it wt-1-et for t > ï as in an AR(2) process. Show that the process mean, E(Y.), is zero. (b) Suppose that (a is generated according to }.-10 e,-tet-+扣-1 with e,-N(0.) 0 Find the mean and covariance functions for (Y). Is (Y) stationary? Justify your...
Time Series transformation Let an annual series Yt be stationary. However, the series transformed and differentiated Dt = ln(Yt) - ln(Yt-1) is stationary. Moreover, we suppose that it obeys the following theoretical model: Dt = -0.12 + 0.75 Dt-1 + et, in which the error term and is a white noise of variance σ2 = 0.012. How can I transform this model to get the original one before the transformation?
If you model a time series Yt using a stationary ARMA process with a nonzero constant (µ unequal to 0) and use it to forecast future values of Yt, then as you forecast further and further into the future, the confidence interval widths for your forecasts will (a) continue to increase and eventually reach arbitrarily large values. (b) gradually decay to zero. (c) cutoff to zero after some lag. (d) converge to a non-zero limiting value.