In most of the Microsoft Project courses, all the activities have the Constraint type set to “As Soon as Possible” by default. Double click on any activity in the Gantt Chart view and the Task Information window opens. Select the ‘Advanced’ tab as shown in the figure below:
Total Float or Total Slack is the amount of time that a task can move later in time without affecting the finish of the project. Microsoft Project calculates the float for you by performing the forward pass and backward pass calculations. During the forward pass calculations, Microsoft Project adds the task duration to the early start to calculate the late start of the task. These calculations provide an early finish date and a late finish date for every task. The difference between the two is the total slack or float.
To calculate the Total Float for any task, we need to follow the following steps:
To view the float in the Gantt chart, go to the "Format" menu and select "Barstyles”. A dialog box similar to the one shown below appears,
2. Browse down to an empty row and type the following details, a. Name : Float Appearance : Select a bar shape, bar pattern and the desired colour From : Finish To : Late Finish b. Name : Neg Float You can add a barstyle by Appearance : Select a bar shape, bar pattern and the desired colour From : Late Finish To : Finish
3. The reason for adding two bars is that the first bar will only be drawn if Finish is earlier than Late Finish. The second bar will only be drawn if Late Finish is earlier than Finish. This is a useful technique to remember for drawing other sorts of bars where you are comparing against another date (such as baseline, deadline etc.)
The following diagram shows the result of adding these barstyles. You can see for the first group of tasks that Task D has total slack of one week. So if you are in the second week of the project and contemplating whether Task B or Task D is more important to get started on, the answer should be clear that it is Task B.
The Neg Float bar appears when your tasks are already too late. A constraint of "Must Finish On" constraint is set on the Finish milestone. In effect this makes Tasks A, B & C late by one day. As you can see, the red bar shows up indicating that they are 1 day late. Task D is still showing 4 days of total slack.
By making this information visible on the Gantt chart it is much easier to see what tasks are the ones which will affect your project completion and which tasks are less critical.
(This is a guest post contributed by Parul Choudhary,PMP)
P:S: You can take a look at our MS Project Online Courses and MS Project Classroom Training.