Turnaround Project Planning Primer
Since there are too many variables involved in performance measurement, it should only occur after a few days or several shifts have been completed, and after the information that such a performance measurement is based upon has been verified and can be trusted.
The important thing to keep in mind is that there will be errors in the data, which are inherent to human nature, to the complexity of the operations, and to the changing nature of the turnaround scope.
However, some of these errors tend to become negligible if they have a common source, such as a single person estimating or reviewing all of the work; reporting progress, etc.. The important thing is to detect a trend. This trend could parallel the schedule but be within a few percentage points above or below the scheduled progress (within three to six percent, depending on the level of confidence in the estimates). Many estimating errors will "balance" out, yielding a usable manpower total.
Therefore, it is important to consider all of these points and to allow for fluctuations in the manpower schedule and actual manpower usage levels. If the scheduling procedures outlined in these Turnaround Project Planning / Management Primers are followed, a trend will be detected, whether manpower utilization is improving or deteriorating.
Manpower utilization is good when the actual manpower from time cards/time sheets is very close to the "earned" manhours calculated for the same time period as the time cards. These two numbers will never be exactly the same; in other words, it is not possible to achieve one hundred percent manpower utilization, because there are always factors not included in the schedule, such as lunch breaks, time to prepare to leave the job site, unexpected delays such as evacuations, accidents, bad weather, etc..
Of course, the PFD (Personal, Fatigue and Delay) factors should have been incorporated into every activity estimate. If there were no such delays as listed above then manpower utilization (or performance) could be one hundred percent.
Detecting deteriorating performance is only detecting a symptom. The cause should be determined and a decision made to eliminate the cause. See the Turnaround Project Planning Primer - Measuring and Reporting Progress page for a description of ATC Professional™ reports that can help in determining the reasons for poor performance.