VOICES In the Trenches
The 20-Percent
Solution
How to stop playing games with your project schedule.
By Ronald B. Smith, PMP
Ronald B. Smith, PMP, recently retired from IBM
Global Services and now teaches project man-
agement to technical graduate students at the
University of Houston, Houston, Texas, USA.
MOST RECENTLY BASELINED project plans are
inaccurate because they have unrealistic start
dates, finish dates, work hours, costs and/or durations. Poor estimating during the planning phase is
a big contributor to project failures.
However, project managers can build more accuracy and credibility into their project plans by incorporating the 20-percent solution into three areas.
REALISTIC SCHEDULES
No one is available to work on projects 100 per-
cent of his or her time—people take breaks, attend
meetings, get stuck in traffic and so on. Therefore,
you should make the assumption a resource is
unavailable 20 percent of the time and avail-
able 80 percent. If a resource is available
only half-time for a project, set the maxi-
mum units of availability at 40 percent. Also
remember to include holidays, plant shut-
downs, training and individual resource vaca-
tions when setting up your project’s schedule.
BUFFER PROTECTION
No plan ever runs according to schedule.
Some tasks will come in late, so you need
some wiggle room. A good idea is to add a buffer
task at the end of selected phases (for example,
phases involving new technology that your team
has limited or no experience using) or to extend
the project’s summary end date for that phase by
20 percent from its original duration. For example,
if the original phase duration is 100 days, extend it
to 120 days.
If you don’t end up using the entire buffer,
reduce the buffer’s duration time to get an accurate
project completion date. If you don’t use any of the
buffer, delete or inactivate it (remove the values
from your rolled-up schedule). In this situation, I
recommend inactivating the task so it is saved for
historical reasons and can be reactivated later if
needed for an emergency.
MANAGING RISKS
Since organizations usually don’t spend enough
time on risk management, contingency funds totaling 20 percent of the total budget should be set up
for each project.
There are two types of risks. Known
unknowns are identified at the beginning of the
project, and unknown unknowns are identified
during the execution of the project. Set up contingency funds of 10 percent of the budget for
each of these risk categories. These safety margins should obviate the need for padding task
estimates (probably the worst habit a project
manager can develop) and similar games, and
help to produce an honest project plan that will
get stakeholder buy-in.
Following these three tips should improve your
project plan’s credibility and performance. If you
discover over time and through lessons learned
that the 20-percent figure is not appropriate for
your organization, adjust to what works best (for
example, 17. 5 percent or 25 percent). PM
No plan ever
runs according
to schedule.
Some tasks will
come in late, so
you need some
wiggle room.
