Level Shift Outlier in Forecasting

[sasgiaz]

Hello again,

I've been doing a project where I use ARI(1,1) with outliers as the model for forecasting.

I'm planning to do the forecast manually through Ms. Excel but I find a problem.

So, here's the model.

The problem is I don't know what will happen to the 1/(1-B) if the I(49) valued as 1.

Thankyou so much for your consideration to help me solve this problem.

Best regards.

[PaigeMiller]

But you can plug-in the value 1 and see what will happen ...

[sasgiaz]

no, I mean since 1/(1-B) is as a constant, something must be doing to the equation before I plug in the valued of I(49).......because I'm going to count it manually