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BETTER ODDS AT BLACKJACK? 143

is 4 weeks, but there is a resource overload in week 1. After resource leveling, the
result should still be 4 weeks, as there is room to move 1 task, within the available
float. Yet several products delayed more than 1 task, underutilizing available re-
sources in week 1, and adding 1 week to the project duration.

In both test cases, it was possible to obtain the optimal solution manually, fol-
lowing a set of pre-defined ordering rules. Yet the process of serial leveling (rou-
tines to immediately place tasks that are ready to be worked), often resulted in
periods of resource underutilization that were unnecessary.

Test model C is the most revealing. It consists of only 3 tasks and 1 resource.
Only 2 of the tasks require the resource. Depending on the ranking factors used,
resource leveling can add either 1 day or 5 months to the schedule. For those pro-
grams that offer a choice of ranking factors, it is up to the user to determine
which method of prioritization will produce the better result.

And don’t look for help from the user manuals and other documentation on re-
source leveling ranking factors. I read, in one manual, that Late Start (LS) will
usually produce the shortest resource-constrained schedule. Another source sug-
gested that least Total Float (TF) should be your first try. Yet, in my experiments,
the best results in test model A were obtained using Early Start (ES) and test
model C worked best with Late Finish (LF) or least (shortest) duration.

Better Odds at Blackjack?

What I learned, from my research and testing, is that the chances of getting 21
were far greater than the chances of obtaining optimal leveled schedules from
project management software. Oh! If only we could employ elastic resources, I
thought, wishfully. But resource pools that grow as needed are even rarer than
the successful cloning of project managers.

No, the only immediate, practical solution (outside of software improvements)
is to recognize the limitations of today’s project scheduling systems, and to work
within these limits. This will require interaction between the person doing the re-
source management and the project management software system.

Tool Tip Good news! Although the serial leveling algorithm
continues to dominate the traditional CPM tools, the results
delivered by the latest releases are more likely to provide a
better solution than the products that I reviewed for my series
of tests. While still benefiting from user interaction, the com-
puted results from these latest releases are much more de-
pendable than they were a few years ago.