How to backcast lost observations due to regular/seasonal differencing in ARIMA procedure?

[Tony_Chan]

Dear Experts,

I would like to seek your help in guiding me in backcasting those lost observations due to differencing to achieve stationarity of a time series. The ARIMA procedure does provide an option called "back=" in the forecast statement. However, it cannot help backcast any lost observations. Please advise.

Thank you very much!

Tony

[Sa_S · Accepted solution]

Dear @Tony_Chan 

For this issue, you might be best served by contacting Technical Support and requesting SAS Content Assessment Tool support.  Here is a link for your convenience: https://support.sas.com/en/technical-support.html#contact 

Thank you for using SAS!

[Tony_Chan]

Dear Expert,

Thanks a lot for your advice!

Tony

[Sa_S]

Thank you for the post- we are responding in your TS case. Thanks, and have a great day!