Project 2013 Intermediate

Lesson 4 – Working with the Critical Path

Project 2013

By default, critical tasks have slack that is less than or equal to zero days. If your critical tasks can have a different amount of slack, you can change this number in the Options dialog box.

Microsoft Project provides two types of slack: free and total . Free slack is the amount of time a task can be delayed without delaying the start date of another task. Total slack is the amount of time a task can be delayed without delaying the finish date of the project. Microsoft Project calculates slack by comparing the difference between the late start date and the scheduled start date with the difference between the late finish date and the scheduled finish date. The smaller of the two differences is the total slack. If the total slack value is negative, the task’s duration is too long for its successor to start at the time designated by a constraint (e.g., a task must start on xx/xx/xx).

You can view slack in the Detail Gantt view. In the left pane, you can view the free and total slack amounts. In the right pane, you can view free slack, represented by the slack bars that join the task bars.

Deadline dates affect the slack amounts for noncritical tasks, but do not affect these amounts for critical tasks. If you have a deadline date set for a task that is not critical, the Total Slack is the amount of time a task can slip and still meet the deadline date. All tasks linked to the task with the deadline date will also be affected by this date. For example, the first three tasks in your task list are linked. The third task has a deadline date that is two days later than the planned finish date. This task will display a total slack value of 2 days .

Likewise, the first and second task will reflect slack values based on the deadline date, not the project finish date. If you remove the deadline date, the noncritical tasks will reflect the true total slack value, which is the number of days the task can slip without affecting the project finish date.

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