num1,num2 etc. are coefficients for other terms you may include in your arima model.. proc arima lets you add other variables (like regressive) into your model using the followin statement:     estimate input=XYZ; referrence: http://support.sas.com/documentation/cdl/en/etsug/63348/HTML/default/viewer.htm#etsug_arima_sect012.htm   hope that helps... if you just have AR term you don't have to worry about the num1,num2 etc. ... View more

i have tried replicating the SAS ARIMA (AR model) model in excel and have been successful for the most part... below is the equation that i am using..    below is the equation for p =(1,7,14) model with no d and q terms Yt = Constant Estimate + ar1*lag1 +ar7*lag7 +ar14*lag14   if the model has other input variables apart from these 3 lags, below is the equation (p =(1,7,14), with input=Temp, with no d and q terms): Yt =  Constant Estimate + ar1*lag1 +ar7*lag7 +ar14*lag14+ num1*Temp-ar1*num1*temp1-ar7*num1*temp7-ar14*num1*temp14   hope this helps. thanks  ... View more