| 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 2nd version (v2a) 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 7-9, 2005.
The section “Interpolation Error” discusses
the partial period along with other sources of error.
The P-Factor 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 Statistical Prediction Calculator is a set of spreadsheets
which produce upper and lower predictions for both final
cost and duration along with their respective “most
likely” results. The set of spreadsheets
includes graphical portrayal of the upper, lower and
most likely project outcomes as a function of time.
Included below are links to the spreadsheet for application,
the application instructions, along with a real data
example application for a late finish project. The
calculator is reasonably simple to apply. The
user does not require in-depth 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.
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