Displaying 20 results from an estimated 6000 matches similar to: "Question about arima.sim()"
2010 Jul 22
0
Please advise acf and pacf in order to determine order of Arima
I have data as below.Please let me know how the ACF and Pacf used to
determine the order od arima model.
Is there any rules need to be followed to determine order.Please advise
> turkey.price.ts
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2001 1.58 1.75 1.63 1.45 1.56 2.07 1.81 1.74 1.54 1.45 0.57 1.15
2002 1.50 1.66 1.34 1.67 1.81 1.60 1.70 1.87 1.47 1.59 0.74 0.82
2006 May 17
1
can Box test the Ljung Box test say which ARIMA model is better?
two ARIMA models, both have several bars signicant in ACF and PACF plots of
their residuals,
but when run Ljung Box tests,
both don't show any significant correlations...
however, one model has p-value that is larger than the other model,
based on the p-values,
can I say the model with larger p-values should be better than the model
with smaller p-values?
[[alternative HTML version
2007 Aug 31
3
Choosing the optimum lag order of ARIMA model
Dear all R users,
I am really struggling to determine the most appropriate lag order of ARIMA model. My understanding is that, as for MA [q] model the auto correlation coeff vanishes after q lag, it says the MA order of a ARIMA model, and for a AR[p] model partial autocorrelation vanishes after p lags it helps to determine the AR lag. And most appropriate model choosed by this argument gives
2011 Feb 25
0
time series with NA - acf - tsdiag - Ljung-Box
Hi all,
I am modelling a time series with missing data.
*Q1)* However, I am not sure if I should use the next *graphics* to
understand my data:
*a)* ACF & PACF (original series)
*b)* ACF & PACF (residuals)
* *
*Q2)* I am using *tsdiag*, so I obtain a graphic with 3 plots: stand.
residuals vs time; acf for residuals; Ljung-Box for residuals (it is wrong
for residuals).
I know that using
2010 Mar 17
1
Reg GARCH+ARIMA
Hi,
Although my doubt is pretty,as i m not from stats background i am not sure
how to proceed on this.
Currently i am doing a forecasting.I used ARIMA to forecast and time series
was volatile i used garchFit for residuals.
How to use the output of Garch to correct the forecasted values from ARIMA.
Here is my code:
###delta is the data
fit<-arima(delta,order=c(2,,0,1))
fit.res <-
2006 Mar 04
1
replicated time series - lme?
Dear R-helpers,
I have a time series analysis problem in R:
I want to analyse the output of my simulation model which is proportional
cover of shrubs in a savanna plot for each of 500 successive years. I have
run the model (which includes stochasticity, especially in the initial
conditions) 17 times generating 17 time series of shrub cover.
I am interested in a possible periodicity of shrub
2009 Sep 29
0
time series and ACF
Hey guys,
im sort of a beginner with R, but here's what i need to do.
i need to perform a time series analysis on a set of financial data that i've been given. im trying to look at the ACF and PACF and fit it to a particular model (i think its the ARIMA model because i've read that financial data resembles the random walk, where the ARIMA model fits). is this correct?
if my data is
2009 Sep 30
0
FW: time series and ACF
Hey guys,
im sort of a beginner with R, but here's what i need to do.
i need to perform a time series analysis on a set of financial data that i've been given. im trying to look at the ACF and PACF and fit it to a particular model (i think its the ARIMA model because i've read that financial data resembles the random walk, where the ARIMA model fits). is this correct?
if my data is
2007 Nov 21
1
problem modeling time series
Good afternoon!
I'm trying to model a ts but unfortunately i'.m very new to this kind of modeling so i 'll be very grateful if you have an advice.
This was my syntax:
2009 May 20
1
stationarity tests
How can I make sure the residual signal, after subtracting the trend extracted through some technique, is actually trend-free ?
I would greatly appreciate any suggestion about some Stationarity tests.
I'd like to make sure I have got the difference between ACF and PACF right.
In the following I am citing some definitions. I would appreciate your thoughts.
ACF(k) estimates the correlation
2006 Apr 27
0
What are the differences between ACF and PACF in time seriesanalysis?
Hello Michael,
see as an online resource:
http://www.statsoft.com/textbook/sttimser.html or get hold on a time
series analysis textbook, like one of the monographies written by
Hamilton; Luetkepohl; Brockwell & Davis; Harvey or Box & Jenkins, to
name but a few.
In a nutshell, PACF 'eliminates' intermediate autocorrelations compared
to ACF, e.g. an AR(1) process will ordinarily
2010 Aug 21
1
How to find residual in predict ARIMA
Dear All,
I have a model to predict time series data for example:
data(LakeHuron)
Lake.fit <- arima(LakeHuron,order=c(1,0,1))
then the function predict() can be used for predicting future data
with the model:
LakeH.pred <- predict(Lake.fit,n.ahead=5)
I can see the result LakeH.pred$pred and LakeH.pred$se but I did not
see residual in predict function.
If I have a model:
[\
Z_t =
2003 Nov 23
0
Stangle - dropping re-used code chunks
My question is: is there a way for Rtangle() to *not* print re-used
code chunks? It'd be easy enough to brew up a perl script to do just
this, but if methods exist already, I'd rather use them. My reading of
the help pages and FAQs has missed something, if it's there.
Background:
I have course notes on R, written using Sweave. I want to provide the R
code separately so the
2007 Dec 01
1
modeling time series with ARIMA
Good afternoon!
I'm trying to model a time series on the following data, which represent a monthly consumption of juices:
>x<-scan()
1: 2859 3613 3930 5193 4523 3226 4280 3436 3235 3379 3517 6022
13: 4465 4604 5441 6575 6092 6607 6390 6150 6488 5912 6228 10196
25: 7612 7270 8617 9535 8449 8520 9148 8077 7824 7991 7660 12130
37: 9135 9512 9631 12642
2010 Nov 29
1
HELPPPPPP
please i've a big problem.
i've to do a econometric-quantitative methods assignment about the canadian
lynx, the problem is that i really i don't know how to use r and how to
apply all the steps.
I begun the time plot, ACF and PACF but i'm not able to decide what is the
correct model of ARIMA, Holt-winter, ecc to forecast the next 20 years of
canadian lynx's cyle...
if someone
2004 Aug 17
1
suggestion for ARMAacf()
hi,
in 1.9.1, the return value from ARMAacf(pacf=TRUE) is not named by lags,
contrary to ?ARMAacf. the simple fix is to move names(Acf) <-
down after if(pacf), with an appropriate starting lag as pacf=TRUE appears
to start at lag 1 (whereas pacf=FALSE starts at lag 0).
for consistency, one could argue to append 1 for lag 0 for pacf=TRUE
(or start pacf=F at lag 1). however, given the
2008 Aug 28
3
Plots spanning columns
Hi! I want to plot three graphs (residuals, ACF and PACF of a
model). Ideally I would use a c(2,2) disposition where the residuals
plot would start at position 1,1 and span to position 1,2. Then I would
plot the ACF in position 2,1 and the PACF in position 2,2. Maybe is
clearer like this:
--------------------------
| |
| residuals |
|
2004 Mar 09
2
corARMA and ACF in nlme
Hi R-sters,
Just wondering what I might be doing wrong. I'm trying to fit a multiple
linear regression model, and being ever mindful about the possibilities of
autocorrelation in the errors (it's a time series), the errors appear to
follow an AR1 process (ar(ts(glsfit$residuals)) selected order 1). So,
when I go back and try to do the simultaneous regression and error fit with
gls,
2010 Feb 11
1
ACF and PACF
Hi helpers,
can you help me in plotting acf and pacf functions in R.
I am using the code
acf(variable name)
but it is not working.
Expecting your reply.
Thanks
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2004 Aug 09
1
Easy acf and pacf for irregular time series in R
R:
Is there an easy way to get the acf and pacf for an irregular times
series? That is, the acf and pacf with lag lengths that are in units of
time, not observation number.
Thanks,
Jason Higbee
Research Associate
Federal Reserve Bank of St. Louis
The views expressed in this email are the author's and not necessarily
those of the Federal Reserve Bank of St. Louis or the Federal Reserve