I am trying to determine the best way to forecast when the data is laid out as follows. I want to predict for 2019, Month 12 by utilizing all of the below data points. And just to clarify, these are Sum YTD totals. So for 2018, we had expensed $135 of our final year end total of $295. So at this point in time last year, we had spent 135/295 = 45.8% of our ending balance.
The forecast options in tableau do not allow me to leverage the 98 sum for 2019, Month 6.
When I add the forecast, the 98 changes into a forecast Estimate. Why is this happening? Is there a way for tableau to leverage these month-to-year correlations when forecasting for an ending balance? For example, if we were to predict that the 45.8% spend pattern would remain steady this year, we could predict our ending 2019 figure would be 98/45.8% = $214.
Attached is the workbook with this example. Any advise is greatly appreciated.