From: <markleeds_at_verizon.net>

Date: Thu, 26 Jun 2008 16:07:30 -0500 (CDT)

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 26 Jun 2008 - 21:10:39 GMT

Date: Thu, 26 Jun 2008 16:07:30 -0500 (CDT)

This is not exactly an R question but the R code below may make my
question more understandable.

I don't have their text in front of me but I don't remember them having
an example such as below when they talk about needing to difference
series

to achieve stationarity. thanks for any insights or a text that talks
about this.

x <- seq(pi,-pi,by=-pi/4)

y <- sin(x)

plot(x,y)

acf(y)

P.S: this question arose because a colleague asked me to look at the
plot of his series and the associated acf and he claims it's a
stationary series and

I'm trying to explain to him that it is not and to try to use the acf to
build a model for it is not reasonable.

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 26 Jun 2008 - 21:10:39 GMT

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