By Cynthia Snyder When you look at a project work breakdown structure in Project , also known as WBS, or a project task list, such as the one shown in the following figure, you see that it organizes tasks into levels.
The upper levels are from the WBS. The lower level consists of tasks that have been decomposed from the WBS. A task that has other tasks indented below it in this outline structure is a summary task, or parent task. The tasks indented below the summary task are subtasks, or child tasks. Summary tasks are indicated in bold in the Project outline.
You can tell when a summary task has a family of subtasks clinging to its skirts: When a subtask is hidden, a little clear triangle is displayed to the left of the summary task. When you click the triangle with the tip of the pointer, the task expands to show its whole clan of subtasks, and the summary task adds a black triangle to its left. Project outline, showing summary tasks and subtasks.
In the figure you can see that the summary tasks of Database and User Interface have hidden subtasks. The Payment and Confirmation summary tasks show all their subtasks. All information about a family of tasks is rolled up into its highest-level summary task. Therefore, any task with subtasks has no timing or cost information of its own: It gathers its total duration and cost from the sum of its parts. This roll-up functionality is cumulative: The lowest-level task rolls up to its parent, which might roll up into another summary task, which rolls up for example into a project summary task.
Any task with tasks below it gets its duration and cost information from a roll-up of its subtasks, no matter how deeply nested it may be in the hierarchy. The structure of families in an outline is also useful when you need to reorganize an outline: To deal with this situation, you can change the summary task to use auto-scheduling, in which case it calculates roll-up data correctly. If you want the summary task to continue to be manually scheduled, you can edit its finish date or use the Task Inspector to fix the summary task schedule.
How many levels can you go in the WBS? You have no practical limit on how many levels of tasks you can create in an outline. At some point, you have to deal with assigning timing and resources to each of these tasks and then track their progress. Too much detail can make your project plan difficult to manage.
Best practices suggest that you always set up your schedule to the level to which you want to manage your team — typically, business working days or weeks. For example, if you have a two-year project, you may have the first three months planned out in detail, the next three months at a higher level, and the remainder of the project schedule showing only milestones and key deliverables. As you progress through the project, you start to add more detail for six months and beyond.
A good rule of thumb is to keep a good amount of detail for 90 days out. The project summary task Just as a ship has only one captain, only one task summarizes all other tasks in a project. Display the project summary task, which represents the highest least detailed level of information and is often simply the title of the project, such as New Product Rollout.
When you tell Project to display the project summary task, every task in the project falls under it in the outline, as shown here. The project summary task. As you build your project, you can easily create a project summary task yourself indent other tasks beneath it or use a Project feature to generate one automatically at any time — even after you build all the phases of your project. To have Project automatically display a project summary task, follow these steps: Notice that the bar for the project summary task on the chart is gray and that the bars for other summary tasks are black.
When you think about it, an upper-level headline in an outline is the sum of its parts: The headline reflects the overall topic for all items below it. The project summary task advances this concept a step further: This task rolls up all actual data from other tasks into one line item.
The length of the summary task, therefore, equals the number of days of work over the course of the subtasks, not the number of calendar days between the start of the first task and end of the last. Not everyone uses project summary tasks. However, having a project summary task has certain benefits: You can quickly view totals for the project at a glance in the columns of data in Gantt Chart view and other views.
You can place a link to your project summary task in another project so that all data for one project is reflected in another.
For example, if you create five schedules for new product launches in your company, you can easily create a master schedule for all company product launches by linking to the project summary tasks in each of the projects.