Disregarding the arguements over SPI, CPI and Earned Schedule, if I wanted to develop a S-Curve chart showing the relevant IEAC forecasts (cumulative) how would I go about this?
the IEAC calculation only provides the estimated at completion cost.
is there some formula to predict periodic values?
To develop the forecast IEAC (Independent Estimate at Completion) curve, you should consider the CPI and forecast progress profile.
The forecast progress profile in turn will consider the present work progress and SPI.
After this, make an assessment for forecast CPI Value. This could be constant or a variable as per your assessment.
IEAC for a particular period = (Periodical Progress target value x Original Budget ) / Forecast CPI for the period
By doing so, you can easily arrive at the IEAC Forecast Curve.
I hope this will help you …