In this lecture,
we will see how time management and scheduling are
performed in practice with the help of the PTB simulator.
Begin by opening the scenario Hard Radar Development.
Our goal is to create a good plan for the project and to follow
through with the execution of the plan until the project is successfully completed.
The first view that we choose after selecting the scenario is the Scenario Info view.
This view displays the information about
what would be considered a timely completion of the project.
In our case, the target date for the project is period 16.
If we are late, that is,
if the project is finished after more than 16 periods,
we will pay a penalty of $20,000 for each period we are late.
On the other hand, if we are early and the project is finished in less than 16 periods,
we will receive a bonus of $10,000 for every period we are early.
In addition to the due date,
information on the project scope or
work content is required for the project time management.
We can see this information as a list of tasks,
along with the precedence relations among the project tasks.
The PTB assumes finish-to-start precedence relations.
Tasks, for example.
The task integration and testing can only start when its three predecessors,
transmitter design, receiver design,
and antenna design are finished.
Another, perhaps more convenient,
way to view this information is the activity on node network diagram.
Click on the "Network" button.
In this network model,
each node represents a task to be performed
and the arrows represent precedence relations among tasks.
The next piece of information required for
planning the project is the duration of the tasks.
In the planning mode,
the duration is forecasted or estimated.
To see the duration of a task, we click on it.
Let's click on the task system engineering.
We can see that the task has two modes of execution,
small team and large team.
For each mode, there are Optimistic,
Most Likely, and Pessimistic Durations.
In real life projects,
it's very hard to precisely predict the duration of a task.
In the PTB, we represent uncertainty in the duration of
tasks by estimating the shortest possible or Optimistic Duration,
the longest possible or Pessimistic Duration,
and the Most Likely Duration.
This three-point estimate is available
for each alternative or mode of performing the task.
The most likely time tells us if the duration distribution is symmetrical or skewed.
For the small team,
those values are five, seven, and 10.
This means that if we perform the task in the small team mode,
as it is currently planned,
the task will take anywhere between five and 10 periods,
with the most likely duration of seven periods.
Click on "Plan default" and select the "Gantt chart".
In the Gantt chart, we can see the current default plan.
This plan has an early start schedule.
In the Gantt chart, each bar represents a project task and
the duration of the task is represented by the lengths of the corresponding bar.
The horizontal axis represents the time since the start of the project.
And the leftmost point of each bar representing the task indicates its start time.
The rightmost point of the bar indicates the task finish time.
In our case, the estimated finish time of the entire project is currently 18 periods.
For example, the task transmitter design is scheduled to start in seven periods.
And since it is likely to take five periods,
it's scheduled to finish in 12 periods.
The reason it is not scheduled to start earlier
is that it can only start once the predecessor tasks,
system engineering, has finished.
We can compute the critical path by calculating the early start,
late start, early finish,
and late finish times for each activity,
or we can do this automatically by clicking on the "Critical task" button.
If we change the duration or start time of a task on the critical path,
it will affect the entire project duration.
Once we know the critical path,
we can choose a late start schedule,
select non-critical activities and delay their start time by the slack.
For example, delay the non-critical task,
transmitter design, by two periods by dragging the task in the Gantt chart.
Delaying non-critical tasks might be useful
for cash flow and resource usage considerations.
The stochastic duration has to be taken
into account when planning and executing the project.
As we run the simulation,
the duration of the tasks will not necessarily be the
same as the most likely duration that we see in the Gantt chart.
Some tasks might take more time to execute, and some, less.
This has to be taken into account when creating
the project plan and when monitoring and controlling the project,
as we will see in later units.
To summarize, scheduling is an important aspect of project management.
And the planning phase is important to make sure
the project schedule is aligned with the due date goals.
Since there is a tradeoff between project duration and project cost,
it's important to make sure that satisfying
one constraint does not cause a violation on the other constraint.
At the execution phase,
the project manager has to verify that the project is advancing as planned.
If it is not, corrective actions must be taken.
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