In the last chapter, you saw how a project can be broken down into a set of user stories which can then be broken down into a list of tasks.
Once you know who will work on each task and how long it will take, then you can put together a project plan that will allow you to track the project's progress. Very simply, create a project plan and the planning phase can then move into the executing and monitoring phases of the project management lifecycle.
Invented by William Gantt, the Gantt chart is a type of bar chart that shows a visual representation of a project plan.
In a Gantt chart:
Tasks are listed vertically - each tasks is represented by one row in the Gantt chart.
Each task is represented by a horizontal bar.
The width of this horizontal bar represents the duration of the task.
The left-hand side of the bar show the calendar day that the task is scheduled to begin. The right- hand side of the bar shows the calendar day the task is scheduled to be completed.
Sometimes one task must be completed before another can begin. Examples of this could be:
A tester cannot test a feature until developers are finished building it.
An engineer cannot build a new web page until the graphic designer has given her the designs in Photoshop.
When one task needs another task to be complete before it can be started, then we say it is dependent on this task, or that it has task dependency.
Project tasks should only be scheduled in your plan to begin after all other dependent tasks have been completed.
Denote dependencies in your Gantt chart. This can be done by using an arrow. In the chart below, the arrows tell you that it is only possible to start Task 2 once Task 1 is complete and that it is only possible to start Task 3 once Task 2 is complete.
2. Critical path
Critical path is the longest path of tasks between the start and end of a project. If you order tasks so that each task is only begun after any dependent tasks have been completed, then the longest path of tasks will tell you the shortest time that this project can be completed.
You can identify a project's critical path in the following way:
List all the tasks in the project.
Note the duration of each task.
Order the tasks so that any dependent tasks are scheduled after those tasks are complete.
Identify the longest path from start to finish (i.e. the path that has the longest time necessary to complete the tasks in that path).
In the chart below, you can see the critical path denoted in orange. The longest path (Task 3, 5, then 6) is 3+3+6 = 12 days. As tasks 3, 5, and 6 are on the critical path, the project duration will be 12 days.
Critical path is useful in the following ways:
Project managers care about critical path because they know that if a task on the critical path is delayed by one day, then the end date of the project is also delayed by one day. In the illustration above, the orange path will take 12 days (critical path). If Task 6 actually took 4 days instead of 3 days, then the project would take 13 days instead of 12. If a task on the critical path is delayed, the entire project is delayed.
In comparison, a late task that is not on the critical path does not necessarily delay the entire project. For example, if Task 2 takes five days instead of three days, then the entire project can still be delivered in 12 days.
For this reason, a project manager will often assign her most effective and experienced people to complete tasks on the critical path. She knows that these tasks potentially have the largest impact on the project's deadline.
If the project must be shortened for some reason, then the project manager will need to shorten time spent on the critical path tasks. Only by reducing the critical path can the project be shortened.
Wikipedia defines a milestone as:
a tool used in project management to mark specific points along a project timeline.
Milestones highlight important moments of a project's progress. Key decision-makers may not track progress on a daily basis, but they will want to see that major milestones are reached. Milestones are also used as a time for external review and quality assessment. In some cases, a review can prompt an increase in the budget if it is needed to continue the project. For this reason, a project manager will often assign her most effective and experienced people to complete tasks on the critical path. She knows that these tasks potentially have the largest impact on the project's deadline.
The author of the project plan should choose milestones carefully. The determined events will help the team stay focused on meeting targets. Therefore, it is important to select important events that the whole team can strive to achieve.
Milestones should be clearly visible on a Gantt chart.
Typically, milestones are denoted as a diamond on a Gantt chart and have a row of their own to make them clearly visible.
Now that you have learned the concepts of task dependency, critical path and milestones, you can incorporate these into the project's Gantt chart. The chart will help create a visual representation of the tasks that you need to complete to complete the project. It will help you monitor project progress and understand if you are making sufficient progress as the project unfolds.
A Gantt chart is a type of bar chart that shows a visual representation of project progress.
A task dependency is when one task cannot start until another one has been finished.
Critical path is the longest path of tasks between the start and end of a project. It tells you how long the project will take.
Milestones are specific points on a project timeline that highlight important moments of progress.