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Examples of Forecast Calculations

A set of examples may help demonstrate how forecast calculations are performed in Cobra.

Assume that you have budgeted 1000 hours for a work package scheduled to start in January and finish in May as follows:

Jan Feb Mar Apr May
150.00 450.00 200.00 100.00 100.00

At the end of the first month you advance the status date one period, and indicate that 10% of the work has been completed. You calculate and post an earned value of 100 hours for the work package, and enter actual costs of 200 hours.

At this point, we can see how Cobra calculates four different types of forecasts, based on the following methods:
  • PF=1
  • PF=User input
  • Manual Forecast (Retain EAC)
  • Manual Forecast (Retain ETC)

PF=1

Cobra recalculates the work package ETC by subtracting any earned portion from the original budget and assuming that any remaining work will be performed according to the budget. This results in a forecast ETC of 900 hours and a forecast EAC of 1100 hours (ETC plus actual costs). Cobra then prorates this new ETC over the remaining periods for the work package as follows:

Feb Mar Apr May
476.46 211.78 105.88 105.88

PF=User input

In this case, Cobra uses a user-defined performance factor of 0.9, which indicates that the remaining work is expected to be performed at 90% of the cost of the original budget. This performance factor results in a forecast ETC of 810 hours for the work package and a forecast EAC of 1010 hours. Cobra spreads this ETC as follows:

Feb Mar Apr May
428.81 190.59 95.30 95.30

Manual Forecast (Retain EAC)

When generating manual forecasts, Cobra ignores any value earned by the work package. With this method, the previous EAC (1000 hours) is retained and a new ETC is calculated by subtracting the actual costs (200 hours) from that figure. The result is a forecast ETC of 800 hours, which is initially spread as follows:

Feb Mar Apr May
423.52 188.24 94.12 94.12
To explain how Cobra calculates forecast of Control Accounts/Work Packages with Planned and In-Progress statuses using the Manual Forecast (Retain EAC) method, let us use the following data:
Jan Feb Mar Apr May
150.00 450.00 200.00 100.00 100.00
Note: The tables below display the results after running the Advance Calendar and then Calculate Forecast.
If Control Account/Work Package has Planned status (no actual costs) and the forecast start is set before the status date, Cobra uses the entire spread profile over the periods after the status date.
Feb Mar Apr May
262.50 437.50 175.00 125.00
Note: If the Allow posting actual costs to a planned Control Account or Work Package option on the Actual Cost Preferences tab of the Project Properties dialog box is selected and there are actual costs prior to the status date, Cobra deducts the actual value then uses the entire spread profile over the periods after the status date.
If Control Account/Work Package has In-Progress status (no actual costs) and the Actual start date is set before the status date, Cobra uses the spread profile for the remaining periods.
Feb Mar Apr May
529.41 235.29 117.65 117.65
If Control Account/Work Package has In-Progress status (no actual costs) and you move the finish date to an earlier date, Cobra uses the remaining periods' spread profile and spreads it over the new dates.
Feb Mar Apr
651.96 260.78 87.26
If Control Account/Work Package has In-Progress status (no actual costs) and you move the finish date to later date, Cobra uses the remaining periods' spread profile and spreads it over the new dates.
Feb Mar Apr May Jun
314.62 370.63 146.44 114.48 53.83

Manual Forecast (Retain ETC)

For this method of generating forecasts, Cobra simply looks at the remaining ETC of the work package and adds any actual costs already incurred. In this example, the calculation results in an EAC of 1050 hours (850 hours of remaining budget plus 200 hours of actuals).

Feb Mar Apr May
450.00 200.00 100.00 100.00