A project schedule is typically presented in the form of a Gantt Chart, but can be found in many other formats. A project schedule is a timetable that shows the (planned and actual) start and end date of all project tasks, how the tasks relate to each other and which team members or other resources are responsible for delivery (Jones, 2009, PMI). We take our work breakdown structure, assign resources, assign responsibilities to specific individuals and plan the timing accordingly.

Why Is It So Important?

Scheduling activities helps to identify dependencies – the logical relationship between tasks. Without dependencies, you cannot possibly prioritize activities. Task dependencies help you build a logical order for all activities involved in your project.

Let’s say you want to make a sandwich. You can break the steps down like this:

1. Slice bread
2. Spread mayo on bread
3. Add cheese/meat/lettuce
4. Combine

You would not spread the mayo on the bread before slicing it, right?

Therefore, the task of spreading the mayo is dependent on the task of slicing the bread.

Dependencies occur when there is a relationships between tasks. Every activity in the schedule will have at least one predecessor and one successor, except for the very first activity and the very last activity. The next task, or group of tasks, cannot begin until the preceding work has been completed (Max Wideman, 2000-2017).

Critical Path Method (CPM)

The critical path is defined as the “longest path through the project” (the minimum entire time to complete the project). While there may or may not be slack in the schedule, the schedule’s longest path to completion is through the critical path (Jones, 2009, PMI).

The CPM is a methodology that helps to determine the most efficient path possible for the project. To implement this method, you follow a 6-step process:

1. Critical Path Method (CPM). Create a list of all activities involved.
2. Build a sequence of activities, considering all the critical dependencies associated with the project.
3. Draw a network diagram. The boxes represent your project’s activities and the arrows indicate the relationships between them.
4. Estimate individual activity duration.
5. Find your critical path – the longest path to complete your project.
6. Update the critical path diagram as needed as the project progresses.

Program Evaluation and Review Technique (PERT)

The PERT method helps you estimate the duration of a project based on 3-point estimates, from which you can calculate the average durations and standard deviations. PERT analysis is commonly represented on network diagrams, like CPM. But where CPM focuses on one-time estimates, PERT uses 3-point estimates for every duration:

• Most likely duration
• Pessimistic estimate
• Optimistic estimate

Based on these estimates, you can forecast an average duration for the whole project. The PERT method suggests you multiply both the optimistic and pessimistic estimates by 1 and the most likely estimate by 4. Then, you divide the result by 6.

If you wanted to take a more pessimistic approach, you could multiply the optimistic estimate by 1, the most likely estimate by 4, and the pessimistic one by 3, and divide by 9. Or you could increase the ‘scoring’ on the most likely estimate.