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2013 Feb 05
1
R -HELP REQUEST
...y for taking your time from your research and
teaching schedules.
If you have a non-stationary univariate time Series
data that has the transformation:
Say; l.dat<-log (series)
d.ldat<-diff (l.dat, differences=1)
and you fit say arima model.
predit.arima<-predict (fit.series, n.ahead=10,
xregnew= (n+1) :( n+10))
How could I re-transform
"prediction$pred" to the level data since it has been differenced once? I know exp (prediction$pred) will bring the inverse of the log
transform but what about the differenced transform? This is my question.
I would be very grateful if you could h...