The Defense Contract Management Agency’s (DCMA) Critical Path Length Index (CPLI) is a forward looking guage of the efficiency required to complete a major milestone on-time, most likely the project deadline. Let’s take a closer look at this interesting metric.
The DCMA missed tasks assessment discussed in a previous article is an early warning alert that the schedule is falling behind. Whether the missed task assessment warns your schedule is falling behind or not, the Critical Path Length Index measures the efficiency required on remaining tasks to meet the project deadline. A CPLI of 1.00 says the project team must accomplish one day’s worth of work for every day that passes.
A CPLI less than one warns that the schedule is progressing inefficiently with regard to meeting the project deadline. A CPLI greater than one is good news; the program is running efficiently with regard to meeting the deadline. The CPLI indicates the efficiency of the critical path, and is a measure of the relative achievability of the critical path.
In Figure 1 we have a demonstration schedule.
This schedule has progressed two weeks. Note the yellow baseline that indicates we are currently ahead of schedule. Also, the ‘BL Project Finish’ lists the project baseline finish dates of all tasks. Note, in particular, that the project complete milestone occurs at the close of business on April 10th, 2018. Let’s create a project finish constraint on this date, and observe the impact on our total float. Figure 2 displays our schedule with an April 10th project constraint.
The remaining duration of the project is 43.8-days and the total float of the project complete milestone is 2.3-days. With this data we can calculate the Critical Path Length Index using the following formula:
The CPLI for our schedule is 1.05, which is good news. The schedule is working along at an efficient pace. If the CPLI was less than 1.00 we would know an increased efficiency is required to meet the project deadline. Again, CPLI is a measure of the realistic possibility of meeting the project deadline. The CPLI assessment also flags any schedule that has a CPLI less than 0.95; this indicates a project in trouble.
The Critical Path Length Index is a measure of the efficiency required on remaining critical tasks to meet the project deadline. It is a forward looking measure, unlike the missed task assessment that is retrospective. Data input required for CPLI are simply CPL and TF, which can be found by defining a project constraint. Not only is CPLI a measure of efficiency, but it also warns when a schedule is in trouble or not meeting the project deadline. CPLI values less than 0.95 triggers a flag that the schedule requires further review.