Hi all i am new to R and was trying to forecast time series data for that i have uplifted data from a site http://www.eia.gov/cneaf/electricity/page/sales_revenue.xls and used their ALL Sector revenue data upto 13000 as train data and rest kept separately for testing of prediction .. now i want to set my model to give closet prediction to test data however i am not getting how to adjust these order and seasonality i have also read http://www.duke.edu/~rnau/arimrule.htm but didnt got anything as o how much should i adjust it .as i m unfamiliar to most of R syntax i m therefore facing more issues..Please post your replies through citing syntaxes in R and hoe to interpret acf and pacf to adjust them -- View this message in context: http://r.789695.n4.nabble.com/Seasonality-and-order-in-Arima-tp4327127p4327127.html Sent from the R help mailing list archive at Nabble.com.