Maintaining a Project’s Completion Date is great but not by implementing what could be considered as concealing or under-handed measures.
In the illustration above, Test Project 1 – Update 01 with Data Date 17-May-20, highlighted Activity “C” is forecast to complete on 07-Jul-20. However, in the Test Project 1 – Update 02 with Data Date 17-Jun-20, Activity “C” has slipped by 14 calendar days to 21-Jul-20.
Miraculously:
- the Project has maintained its Completion Date at 01-Sep-20 and;
- The Finish date for Activity “D” remains at 28-Jul-20.
How did this happen?
There are many ways to manipulate a CPM network to mask lack of progress. One typical way involves introducing either a negative lag or reduced lag values especially along the critical path.
In the example above, The FF lag between Activity “C” and Activity “D” was reduced from 15 to 5 days, and a lag of -10 days was introduced into the FS relationship between Activity “C” and Activity “E”.
These subtle changes are difficult to detect since the graphical representation of the logic relationships are remarkably similar as shown in the illustration above. In a large CPM network, lag changes of this type can be easily missed.
Zümmer identifies these changes under Comparison Report #08 – “Logic Changes To Lag Only”. In the illustration below, Line Item #1 reports the FF lag change from 15 days to 5 days between Activity “C” and Activity “D” and; Line Item #2 reports the introduction of a FS negative lag of -10 days between Activity “C” and Activity “E”.
Since Lags are a property of Logic Relationships, a change in the Lag value is considered a change to the CPM logic and is reported as a logic change in other Zümmer comparison reports.
If you are receiving periodical CPM schedule updates and encounter these type of changes, it is especially important to report these issues back to the submitter so that further CPM logic changes of this type are prevented.
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