Displaying 20 results from an estimated 10000 matches similar to: "using arima() function"
2001 Apr 24
1
ARIMA and GARCH
Hello,
I would like to study time series with ARIMA and GARCH models.
I installed R-Plus and its libraries but when I try to execute the function
arima0, It answers that the function does not exist.
Could you help me or give me references of papers dealing with arima and garch
in R-Plus?
Thanks
Beno?t,
___________________________________
Mr. Beno?t LACHERON
Rue de l'industrie, 44,
1040
2000 Dec 30
3
ARIMA
Thanks,
Can't find an ARIMA in base, dse1/2 or tseries, only references to. What
package is it in?
Thanks again!
Best regards,
/fb
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2001 Dec 16
3
Arima
I did a regression with ARMA errors using arima0 with
ari<-arima0(y,order=c(2,0,2),xreg=reg1,delta=-1)
or
ari<-arima0(y,order=c(2,0,2),xreg=reg1)
where reg1 is the matrix of the regressors and when I see diag(ari$var.coef)
I get negative terms. Do you know what this mean ?
I try to change transform.pars to 0 or 1 but this crash R on Windows.
Is it possible to test the significativity
2004 Aug 29
1
predict(arima)
Dear All,
R 1.9.1, Windows
When copying and pasting a few lines from the 'predict.Arima' help, I
get an error message:
> data(lh)
> predict(arima(lh, order = c(3,0,0)), n.ahead = 12)
Error in eval(expr, envir, enclos) : Object "xreg" not found
On the other hand, the following is OK:
> data(lh)
> predict(arima0(lh, order = c(3,0,0)), n.ahead = 12)
$pred
Time
2007 Mar 13
1
estimating an ARIMA model with constraints
Hi,
I am trying to estimate an ARIMA model in the case where I have some
specific knowledge about the coefficients that should be included in the
model. Take a classical ARIMA (or even ARMA) model:
P(B) X(t) = Q(B) epsilon(t),
where X(t) is the data, epsilon is a white noise, B is the backward operator
and P and Q are some polynoms. Additionally, assume that you know in advance
how P and Q
2004 Jun 17
1
Error with arima()
Could someone please give a brief explanation, or pointer to an explanation,
of the following error:
> arima(ts.growth, order = c(1,0,0),include.mean=T)
Error in arima(ts.growth, order = c(1, 0, 0), include.mean = T) :
non-stationary AR part from CSS
and why it does not arise with
> arima0(ts.growth, order = c(1,0,0))
Many thanks
____________________________
Dr. Daniel P. Bebber
2009 Apr 22
1
arima
Hi,
I have a suggestion for the fonction arima and arima0. I think you
should not call the constant an intercept because it creates confusion.
It is not really an intercept but a mean. For an AR(1) the intercept mu
should be defined as:
X(t)=mu + phi X(t-1) + e(t)
What you call intercept mu is rather defined as
(X(t)-mu) = phi (X(t-1)-mu)) + e(t)
which is not a common way to define an
2003 Apr 30
2
Bug in arima?
I'm using the fixed argument in arima. Shouldn't ar4, ar5, and ar6
display as zero in the output?
Call:
arima(x = window(log(hhprice), start = c(1990, 1), end = c(2003, 3)),
order = c(7,
1, 0), xreg = window(ts.union(exa1 = lag(exa, -1), exa12 = lag(exa,
-12), exb1 = lag(exb, -1), exc1 = lag(exc, -1), exc12 = lag(exc,
-12)), start = c(1990, 1), end = c(2003, 3)),
2006 Oct 19
1
predict.Arima question
Hi,
I am trying to forecast a model using predict.Arima
I found arima model for a data set: x={x1,x2,x3,...,x(t)}
arima_model = arima(x,order=c(1,0,1))
I am forecasting the next N lags using predict:
arima_pred = predict(arima_model,n.ahead = N, se.fit=T)
If I have one more point in my series, let's say x(t+1). I do not want to
recalibrate themodel, I just want to forecast the next N-1
2007 Jan 16
2
ARIMA xreg and factors
I am using arima to develop a time series regression model, I am using arima
b/c I have autocorrelated errors. Several of my independent variables are
categorical and I have coded them as factors . When I run ARIMA I don't
get any warning or error message, but I do not seem to get estimates for all
the levels of the factor. Can/how does ARIMA handle factors in xreg?
here is some example
2007 Mar 16
3
Unhidden predict methods
Hi,
I've noted that not all `predict' methods are hidden in the namespace:
> methods("predict")
[1] predict.ar* predict.Arima*
[3] predict.arima0* predict.glm
[5] predict.HoltWinters* predict.lm
[7] predict.loess* predict.mlm
[9] predict.nls* predict.poly
[11] predict.ppr* predict.prcomp*
[13]
2008 May 08
1
ARIMA, AR, STEP
Here is my problem:
Autoregressive models are very interesting in forecasting consumptions (eg water, gas etc).
Generally time series of this type have a long history with relatively simple patterns and can be useful to add external regressors for calendar events (holydays, vacations etc).
arima() is a very powerful function but kalman filter is very slow (and I foun difficulties of estimation)
2004 May 24
1
Null model for arima.sim().
In some time series simulations I'm doing, I occasionally want the
model to be ``white noise'', i.e. no model at all. I thought it
would be nice if I could fit this into the arima.sim() context,
without making an exceptional case. I.e. one ***could*** do
something to the effect
if(length(model)==0) x <- rnorm(n) else x <- arima.sim(model,n)
but it would be more suave if one
2007 Aug 23
1
Estimate Intercept in ARIMA model
Hi, All,
This is my program
ts1.sim <- arima.sim(list(order = c(1,1,0), ar = c(0.7)), n = 200)
ts2.sim <- arima.sim(list(order = c(1,1,0), ar = c(0.5)), n = 200)
tdata<-ts(c(ts1.sim[-1],ts2.sim[-1]))
tre<-c(rep(0,200),rep(1,200))
gender<-rbinom(400,1,.5)
x<-matrix(0,2,400)
x[1,]<-tre
x[2,]<-gender
fit <- arima(tdata, c(1, 1, 0), method = "CSS",xreg=t(x))
2003 Mar 11
1
MAPE
Hi again
With arima0 the problem was solved but what are the diferences
between arima and arima0?
I have another question. I fit the model to the data and I make
some predictions. But I also want to calculate MAPE based in
the last 3 observations available. Is it possible? Can I obtain
the fitted values from the model?
thanks~
luis
--
SAPO ADSL.PT, apanhe j? o comboio da Banda Larga. Kit
2005 Oct 10
1
using innov in arima.sim
Hello,
I have used the arima.sim function to generate a lot of time series, but to day I got som results that I didn't quite understand. Generating two time series z0 and z1 as
eps <- rnorm(n, sd=0.03)
z0 <- arima.sim(list(ar=c(0.9)), n=n, innov=eps)
and
z1 <- arima.sim(list(ar=c(0.9)), n=n, sd=0.03),
I would expect z0 and z1 to be qualitatively similar. However, with n=10 the
2005 Oct 02
2
arima.sim bug?
Hi,
I am using the arima.sim function to generate some AR time series. However, the function does not seem to produce exactly the same time series when I specify the innov parameter. For example
> r <- rnorm(300)
> x <- arima.sim(300, model=list(order=c(1,0,0),ar=c(.96)), innov=r, n.start=10)
> y <- arima.sim(300, model=list(order=c(1,0,0),ar=c(.96)), innov=r, n.start=10)
>
2004 Mar 22
1
problem with seasonal arima
hallo to all
I've to calculate an arima model and I need only the
first and 365 th parameter and also the sar1 and the
intercept, so I'm traing with:
arima(X,order=c(365,0,0),seasonal=list(order=c(1,0,0),..),fixed=c(NA,rep(0,363),NA,NA,NA),transform.pars=F)
but the error answer is:
Error in polyroot(z) : polynomial degree too high (49
max)
also there are problems in allocating memory
2010 Aug 19
1
How to include trend (drift term) in arima.sim
I have been trying to simulate from a time series with trend but I don't see
how to include the trend in the arima.sim() call. The following code
illustrates the problem:
# Begin demonstration program
x <- c(0.168766559, 0.186874000, 0.156710548, 0.151809531, 0.144638812,
0.142106888, 0.140961714, 0.134054659, 0.138722419, 0.134037018,
0.122829846, 0.120188714,