## Using Project Scheduler

Example one features a general purpose CPM program that also offers support for the three time estimate (PERT) approach. Several products have a PERT capability, but we will look at Project Scheduler 8, from Scitor, because of some of its special PERT features.

In PS8, we can activate the PERT mode and add a PERT DUR column to the task table. We can enter the three time estimates, and (in a special PS8 feature) adjust the weighting factors. In Figure 6.3a, we can see that (using the traditional 1/4/1 weighting) the calculated project duration is 21.33 days (vs. the 20 days using the single estimates).

By adjusting the weight factors, we can calculate various degrees of optimism or confidence. Using a 1/0/0 weighting, we calculate the project using only the optimistic durations. In this case we can say that the best possible project end date is 10/16 or 16 days. By changing to a 0/0/1 weighting (all pessimistic) we can project a worst case of 11/1 or 32 days.

Another option is to deliberately add time contingency, by giving more weight to the pessimistic dates. In the model above, setting the weight factors to 1/4/5

Figure 6.3a PERT Mode in Project Scheduler 8 (Scitor)

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0d will generate a 25.6 day schedule. While PS8 has this unusual capability to select the weighting factors, it does not provide support for statistical analysis and probability of various end dates (normally expected in a PERT-type program). Our next two examples do.