What are the units of each variable in the work equation? These units differ depending on which scheduling tool you use.
The work equation is an important concept in scheduling. It specifies how you want the software to behave when adding additional resources to a schedule. A recent student mentioned that when interviewing job candidates he asks them questions to find out whether they are familiar with the elements of the work equation.
Elements of the work equation are usually depicted on the duration triangle. I pointed out that the job candidate’s response may differ depending on whether they are referring to Primavera P6 or Microsoft Project. Duration triangle variable units differ between the two scheduling programs.
This article provides a quick tip to understand work equation units in Primavera P6 and Microsoft Project.
Let’s begin by defining the work equation as follows:
The effort variable is the resource daily effort. The work equation units of a Primavera P6 schedule are accordingly:
These variables are depicted on the Primavera P6 duration triangle, Figure 1.
Figure 1
Work is referred to as hours or simply units. The resource daily effort is units/time. These variables in the work equation are slightly different in Microsoft Project:
And the Microsoft Project duration triangle:
Figure 2
You must be careful to note your scheduling software nomenclature when considering the units of work and effort in the work equation. Units in Primavera P6 is work. But units in Microsoft Project is resource daily effort. So there is a difference between scheduling software programs. Table 1 summarizes the discrepancy.
Figure 3
Units (hours) in Primavera P6 is work, whereas in Microsoft Project units is resource daily effort. And resource daily effort in Primavera P6 is units/time. Duration is equivalent in both software programs.
Summary
It is important to become familiar with the work equation in both Microsoft Project and Primavera P6. And it is easy to confuse work and resource daily effort nomenclatures when referencing the two scheduling software programs. The work equation and proper variable units becomes particularly important when considering the assignment of additional resources.