The Earned Schedule (ES) calculators
are freely available and downloadable from this site. There
are two Excel spreadsheets. The one most used (v1)
does not account for partial periods, that is, the first
period and the last. The second version (v2) does account
for partial periods.
The v1 calculator assumes in the calculations that all
periods are full and not partial. Once several periods
are involved in the calculation, the error introduced becomes
negligible. For those that are applying ES to weekly
Earned Value, the error is small from the outset.
For a discussion of the error in the ES calculation please
reference the Presentations page for the .pdf file, “Earned
Schedule Training,” 17th IIPMC, Nov 79, 2005.
The section “Interpolation Error” discusses
the partial period along with other sources of error.
The special case ES calculator is intended for small projects having downtime and stop work conditions. The calculator produces special indicators and forecasts. Comparison of the special to uncorrected ES forecast is made available.
The PFactor calculator is a set of Excel spreadsheets.
From the baseline schedule and actual performance, the
calculator provides a numerical indicator of how well
the schedule is followed, i.e. a measure of “schedule
adherence.” Other outputs from the calculator
are the identification of tasks which may be experiencing
constraints or impediments, forecast of final cost and
duration, high and low outcome prediction, and probability
of meeting the project cost and schedule commitments.
The Schedule Adherence and Rework Calculator utilizes the periodic values for the Pfactor and the EV accrued to compute and graph the EV accomplished out of sequence and the rework it causes.
The Prediction Analysis Calculator identifies the likelihood that the project will complete at a desired time (ED). The spreadsheet determines the point at which the project exceeds the threshold and becomes “out of control.” The calculator is useful for assessing the opportunity for project recovery and having a successful outcome.
Statistical Forecasting Calculator (v2c) computes high and low confidence limits for final cost and schedule duration. The calculator is reasonably simple to apply. The user does not require indepth understanding of statistics.
Statistical Planning Calculator (Probability &
Reserves) is intended to assist planning teams for strategizing
the amounts of cost and schedule reserve needed to achieve
a desired probability of success. Use of the calculator
requires either estimates or historical variation from
past projects.
The Stability Point Calculator determines the observation
number in a sequence of CPI and SPI(t) values at which
all subsequent observations are within a defined stability
limit.
