Time Centric Principles

The main idea behind the time-centric earned value system is to set a PMB based on planned work package starts and finishes over the course of the project. Time-centric earned value is very close to the concept of "work units" or "standard units of work" as a measure of accomplishment rather than a specific dollarized WBS cost account. Instead of a standard unit of work, however, time-centric earned value focuses on a completed task, with unknown actual cost, as the unit of value in the project.

Although a dollar value is not assigned to each work package start or finish, the total collection of starts and finishes, if executed completely, does represent the total scope (and value) of the project. The total scope of the project does have a dollar planned value (budget).

The historical reporting for purposes of determining variances remains a component of the time-centric system. Instead of earning a dollar value, what is earned is a start or a finish. The PMB is a set of planned starts and planned finishes. Therefore, there is a variance that can be defined thus:

Variance (start) = Earned starts - Planned starts Variance (finish) = Earned finishes - Planned finishes

All the rules we have discussed about what constitutes a claim of credit apply. The definitions of start and finish used in the traditional method to gate the expenses for purposes of calculating the variances to the earned and planned value still apply, but apply to whether a task start can be claimed and not whether actual cost is to be applied. So too do the ideas of rebaselining, calculating the ETC, and the EAC still apply, but apply to the idea of finishing the project on a time basis and not a cost basis.

Time-centric indexes can also be defined and calculated:

Task start performance index (TSPI) = (Earned starts)/(Planned starts) Task finish performance index (TFPI) = (Earned finishes)/(Planned finishes)

Figure 6-5 provides an illustration of a project wherein the PMB has 20 starts in the first three periods. We see in this figure that the project team has indeed started 20 tasks, but the starts are at a different pace than planned. We can calculate a variance for each period:

Start variancei = 3 - 5 = -2 starts Start variance2 = 9 - 10 = -1 start

Start variances Start variance4 S (All variances)

Monltil MoninS Wontfi 3 toPtM

Figure 6-5: Time-Centric Project Start Example.

Monltil MoninS Wontfi 3 toPtM

Figure 6-5: Time-Centric Project Start Example.

At the end of four periods, the project is caught up on starts. The project manager can also forecast how soon the project will attain all the starts planned in the PMB using the performance indexes. Table 6-6 provides the start performance metrics. Similarly, we see in Figure 6-6 the finish performance for the example project. Variances similar to the start variances can be calculated; indexes can also be calculated as was done for the project starts. Table 6-7 provides those calculations.

Table 6-6: Start Performance Project Example

Planned Starts by Month H

Actual Starts by

Month

Monthly Index

Cumulative Index

Forecasted Finish

Month 1: 5 starts

Month 1: 3 starts

Remaining = 17

Cum = 3/5 = 0.6

Adjusted remaining starts = 17/0.6 = 28

Forecast schedule remaining = 2 months * 28/17 = 3.3 months

Month 2: 10 starts

Month 2: 9 starts

TSPI2 = 9/10 = 0.9

Cum Starts = 12

Remaining = 8

Cum = 12/15 = 0.8

Adjusted remaining starts = 8/0.8 = 10

Forecast schedule remaining = 1 month * 10/8 = 1.25 months

Month 3: 5 starts

Month 3: 6 starts

Remaining = 2

Cum = 18/20 = 0.9

Adjusted remaining starts = 2/0.9 = 2.2

Forecast schedule remaining = 0 months * 2.2/2 = 0 months (no remaining schedule available)

Month 4: 0 starts

Month 4: 2 starts

TSPI4 = 2/0 = indefinite

Cum Starts = 20

Remaining = 0

Cum = 20/20 = 1.0

Adjusted remaining starts = 0/1 = 0

Forecast schedule remaining = 0/0 = indefinite

[*lSee related figure for a graphical presentation of this example.

Table 6-7: Finish Performance Project Example

Planned Finishes by Month

Actual Finishes by Month

Monthly Index

Cumulative Index

Forecasted Finish

Month 4: 3 finishes

Month 1: 3 finishes

Remaining = 17

Cum = 3/3 = 1.0

Adjusted remaining finishes = 17/1 = 17

Forecast schedule remaining = 2 months * 17/17 = 2 months

Month 5: 10 finishes

Month 2: 7 finishes

TFPI2 = 7/10 = 0.7

Finishes = 10

Remaining = 10

Cum = 10/13 = 0.77

Adjusted remaining finishes = 10/0.77 = 10.4

Forecast schedule remaining = 1 month * 10.4/10 = 1.04 months

Month 6: 7 finishes

Month 3: 6 finishes

TFPI3 = 6/7 = 0.86

Finishes = 16

Remaining = 4

Cum = 16/20 = 0.8

Adjusted remaining finishes = 4/0.8 = 5

Forecast schedule remaining = 0 months * 5/4 = 0 months (no remaining schedule available)

Month 7: 0 finishes

Remaining = 0

Cum = 20/20 = 1.0

Adjusted remaining finishes = 0/1 = 0

Forecast schedule remaining = 0/0 = indefinite

t*lSee related figure for a graphical presentation of this example.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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