Schedule Updating and Project Control - Construction Project Scheduling and Control - page 187

Only the weights (in the first column) are subjectively assigned. All other columns
are either measured or calculated. Following is a sample calculation for the studs:

Equivalent MBF = Assignedweight ∗ Total MBF

= 0 . 40 ∗ 3 . 50 = 1 . 40

and

Earned MBF = Equivalent MBF ∗ Completed quantity∕Total quantity

= 1 . 40 ∗ 210∕320 = 0 . 92

The weighted or equivalent units method and the incremental milestones method
are similar. Both are used for relatively large and complex activities that comprise
several subactivities. The main difference is that subactivities in the incremental
milestones method must occur in chronological sequence. So, when you assign a
percent complete to a subactivity, you use the cumulative percent complete, which
includes the percent complete for the preceding steps (subactivities). In the weighted
or equivalent units method, subactivities may be somewhat independent. Each
subactivity has its own percent complete regardless of the percent complete for other
subactivities.
You may wonder what the wisdom is for considering a wall-framing “activity” as
a single activity with seven “subactivities” rather than simply having seven individ-
ual activities. One minor advantage that you are able to tell the percent complete for
the entire wall-framing activity. This author prefers to treat the situation as a number
of individual activities. Many scheduling software programs can calculate the percent
complete of a number of activities, grouped under certain criteria. Oracle Primav-
era P6 can do so in one of two ways: (a) you identify the wall-framing activities, for
example, with an activity code (e.g., Step = Framing) and then group activities by
step, or (b) you create a “level of effort 7 ” activity (call it Framing ) that encompasses
all wall-framing activities. Another alternative is to use the work breakdown structure
(WBS) (an example of a WBS is provided in Figure 4.1) and then summarize the WBS
at a certain level. In Microsoft Project, you can “indent” activities to make them sub-
activities. If the major activity has a WBS code of 5, its subactivities will have WBS
codes of 5.1, 5.2, 5.3, and so forth.

Methods for Determining Percent Complete for the Entire Project

We have shown how to estimate the percent complete for individual activities. The
next question is, “What is the percent complete for the entire project?” The answer is
not clear. In fact, there might be several answers—all substantially different—yet none
is the “right” one and none is “wrong.”

7 Used to be called Hammock activity. The author prefers the old name.