Good morning to you all,
Sorry 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 help me with
this.Thank you very much in anticipation

Mr. Mahmoud Coker
Senior Manager 
Bank of Sierra Leone 
(Sam-Bangura Building) 
Freetown-Sierra Leone
West Africa
Email: cokiestarr@yahoo.com
Phone: +232 78 625967 / +232 77 440143
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