The Official Site for Zümmer – CPM Schedule Analysis & Comparison – Page 7 – Copyright ©2012-2026 FoxQuest Systems, Inc.

How To: Perform a CPM Schedule Analysis

Analyzing P6 CPM schedules in Zümmer is easy and intuitive!

Step 1:

From the Schedule Analysis & Comparison Module shown above, select the Project ID listed in either the Control or Modified grid. As you select, the 2 tab descriptions to the right of the “Project Selection” adjust accordingly.

Step 2:

Click on either Tab #2 or #3. Then move the reports from Available Reports list to the Select Reports list. In the illustration above, Analysis Reports 1 thru 20 are selected are ready for printing or previewing.

Check the “Include Summary” checkbox to print a Summary Analysis Report after all selected reports are printed. Lastly, click either Print or Preview and you’re done.

How To: Identify and assess “Out of Sequence – In Progress Tasks”

Since a CPM Network is a “model” of reality, it’s likely that the actual activity sequence will differ from (i.e. out-of-sequence) the planned sequence. Therefore, identifying, assessing and adjusting in response to out-of-sequence events are necessary components to maintaining a functional and high-quality CPM schedule.

In general, the more out-of-sequence activities in the CPM network, the more likelihood that logic revisions are necessary. Zümmer’s Analysis Report # 24 – Out of Sequence in Progress Tasks Report not only lists the “In Progress” tasks that are out-of-sequence but also sorts the activities in order of # Days out-of-sequence.

In the illustration, the schedule is calculated using Retained Logic and the Data Date is 20-May-16. Task D started out-of-sequence and the calculated Early Start is 09-Jun-16. Zümmer defines the # of Days out-of-sequence as the difference between the Early Start and the Data Date. In this case, Task D is out-of-sequence by 20 Days.

Other Zümmer Analysis Reports that relate to Out-Of-Sequence type conditions include:

Analysis Report #23 – Not Complete with Started Successor and:

Analysis Report #25 – Not Started with No Active Predecessors.

Tracking Activities With Constraints

Constraints allow a CPM network to model external dependencies that are outside of the standard predecessor-successor logic. P6 allows for various types of constraints. Unfortunately, keeping track of activities with constraints can be a difficult task especially if both Primary and Secondary constraints are used.

It’s important to realize that overly assigning constraints to a CPM network works against the algorithm date calculations during the forward and backward pass. Constraints should be kept to an absolute minimum. Also Constraints should be totally understood as to exactly how they affect the Early/Late Start/Finish dates as well as the Total Float value.

In the Illustration above, the 9 possible Primary Constraints and 2 possible Secondary Constraint are listed.

Activity Name with Embedded Double Space

The Filters Module in P6 is a very powerful tool. However, when using – the “Activity Name equals/contains” option, problems could arise when Activity Names contain embedded double spaces. For example, in the illustration below, there are 4 ‘Review Bids’ activities. In this case, setting a Filter specification to: “Activity Name contains ‘Review Bids'” will only return 2 results. This is because 2 of the 4 activity names have embedded double spaces.

Checking for this condition using P6 alone is difficult and nearly impossible even in a moderately sized CPM Network.

In Zümmer Analysis Report #02, “Activity Names with Embedded Double Space”, not only lists all instances, but the ‘Set Group’ column even shows you where to look. Using Zümmer concurrently with P6 helps speed the process of eliminating embedded double spaces.

Reporting & Monitoring Analysis Variances

If a Schedule Analysis is a valuable tool for maintaining high-quality CPM networks, then the next logical step is to monitor and report on the progress of analysis results as schedule updates are submitted on a periodic basis.

For example, if you’re an Owner’s Representative and are receiving monthly schedule updates from a Contractor, then monitoring and reporting analysis trends is a great way to ensure that high-quality CPM networks are consistently submitted.

In Zümmer, any 2 Schedule Analysis runs can be compared for variances.

In the illustration above, an analysis was performed for TST-BL4-UP02 (DD 01-Jul-18), then later an analysis was performed for TST-BL4-UP03 (DD 01-Aug-18). Running the Zümmer Analysis Variance report reveals that when compared to the previous analysis, the number of open-ends has increased (+1 for No Predecessors and +7 for No Successors).

Reporting & Monitoring Comparison Variances

If a Schedule Comparison is a valuable tool for maintaining high-quality CPM networks, then the next logical step is to monitor and report on the progress of comparison results as schedule updates are submitted on a periodic basis.

For example, if you’re an Owner’s Representative and are receiving monthly schedule updates from a Contractor, then monitoring and reporting comparison results is a great way to ensure high-quality CPM networks are consistently submitted.

In Zümmer, any 2 Schedule Comparison runs can be compared and checked for variances. In the illustration above, a comparison was performed between Update 03 and Update 04, and then later a comparison was performed between Update 04 and Update 05.

Running the Zümmer Comparison Variance report reveals that when compared to the previous comparison, the number of logic changes has increased (+33 for Added Logic and +1 for Deleted Logic).

Expense Profile with Negative Total Float

When an activity has a negative Total Float value it means the activity cannot complete in time to satisfy an imposed Finish constraint on itself or on another successor activity along its path. Under this condition, the Late Start and Finish dates are actually EARLIER than the Early Start and Finish dates. In an expense loaded schedule, the effects of negative Total Float can be observed in the profile results on the Late Cost Distribution Curve.

In the illustration above, the Project has an imposed “Must Finish By” constraint date. Schedule Progress Update indicates that the Project will not finish on time evidenced by Activities with Negative Total Float values.

In this case, the resulting Late Cost values plots a curve that is ABOVE the Early Cost curve. In some instances, the Late Cost curve can even begin prior to the Data Date. The further left the Late Cost curve begins the more severe the Finish constraint has on the Cost profile and the more difficult recovery based on Cost will be. In addition, Late Cost Curves with Negative Total Float calculations have a tendency of flattening out prior to the Project End Date. Again, the earlier the Late Cost Curve flattens out, the more severe the Negative Total Float values exist on the Project.

In any case, the Early Cost curve remains the same regardless of Finish Constraints imposed on the Project. To produce an Expense Profile curve with a Late Cost Curve relative to the current status of the Project, remove the late constraints, the recalculate the schedule. This will remove the negative Total Float values and generate positive Total Float value.

Retained Logic, Progress Override and Actual Dates

Retained Logic, Progress Override and Actual Dates

There are many of articles regarding this topic on the internet. If you’re still not clear about the difference, below is an explanation presented as simply as possible.

In the illustration above, Activity B is assigned an Actual Start and Actual Finish date LATER than the Data Date. This condition is not considered “best practice” since there should be no Actual Dates later than the Data Date; however, this assignment is necessary to illustrate the difference between Actual Dates and Retained Logic. When there are no Actual Dates later than the Data Date, then Actual Dates and Retained Logic generally behave the same. The difference among the 3 options is reflected in the different Start and Finish dates for Activity C.

In Figure 1, using ACTUAL DATES, Activity C starts after the Actual Finish date for Activity B.

In Figure 2, using RETAINED LOGIC, Activity C ignores the Actual Dates of Activity B and starts after the Finish Date from Activity A.

In Figure 3, using PROGRESS OVERRIDE, since Activity B is “progressed” with Actual Dates, Activity’s C logic is “overridden” and therefore starts on the Data Date.

In summary, the method used to schedule the CPM network could have significant differences in determining the Start and Finish dates. Most contract specifications require the use of Retained Logic. There are many articles that can be found on the internet that cover this issue in greater detail to include effects on earned value and other properties.