Predecessors connect tasks that depend on one another. When you add a predecessor to a task, Project Insight uses its intelligent scheduling engine to calculate the task dates and automatically reschedule dependent tasks when the project schedule changes.
A predecessor is a task that must start or finish before another task can start or finish. The dependent task is called the successor.
Predecessors can be added while editing a task, directly from the task list, or visually from the Gantt chart. A task may also have more than one predecessor.
How predecessors affect the project schedule
Predecessor relationships create a sequence between tasks. For example, a project may require the team to gather requirements before performing planning, and complete planning before developing the product.
When the start date, finish date, or duration of an earlier task changes, Project Insight automatically recalculates the dates of its dependent tasks. This allows you to update the project plan without manually changing every task in the sequence.
The easiest way to see these relationships is on the Gantt chart. Dependency lines show which tasks are connected and the order in which the work is scheduled.
How to add a predecessor while editing a task
- Open the task that will depend on another task. This is the successor task.
- Open the Predecessors section or tab.
- Select Add Predecessor.
- Choose the task that must occur before or in relation to the current task.
- Select the dependency type.
- Add lead or lag time when needed.
- Save the task.
Project Insight calculates the successor task's dates based on the selected predecessor, relationship type, task duration, work schedule, and any lead or lag time.
The image below shows the predecessor interface on the full task edit screen.
Project Insight does not recommend setting predecessor relationships on summary tasks, based on PMBOK scheduling methodology. In most cases, dependencies should be created between the individual tasks contained within the summary tasks.
Predecessor settings
The predecessor window defines the relationship between the task you are editing, called the successor, and the task that comes before it, called the predecessor.
Task
Task allows you to select the task that will become the predecessor. When Cross-Project Dependencies are enabled, you may also be able to select a predecessor from another project.
Lead and lag time
Lead/Lag controls the amount of time between the predecessor and successor tasks.
- Lag time creates a delay between the related tasks.
- Lead time allows the successor to begin before the predecessor relationship would otherwise permit it to begin.
Enter the number of days, hours, or minutes to apply. Leave the value at zero when no lead or lag time is required.
Whole-day values are generally recommended to avoid unnecessarily complex scheduling calculations involving hours and minutes.
Dependency type
Type determines how the predecessor and successor tasks are connected.
- Finish-to-Start: The successor task cannot start until the predecessor task finishes. This is the default and most commonly used dependency type.
- Start-to-Start: The successor task cannot start until the predecessor task starts.
- Finish-to-Finish: The successor task cannot finish until the predecessor task finishes.
- Start-to-Finish: The successor task cannot finish until the predecessor task starts.
How to create a dependency on the Gantt chart
You can also create a predecessor relationship visually from the Gantt chart.
- Open the project's Gantt chart.
- Locate the task that should occur first.
- Drag the dependency connector from the predecessor task bar to the successor task bar.
- Confirm that the dependency line appears between the two tasks.
Project Insight creates the predecessor relationship and recalculates the task dates automatically. You can click the predecessor information from the task list or open the task to review or edit the relationship.
Finish-to-start dependency example
Suppose a task called Prepare Samples cannot begin until Budget Approval is complete. You would create a finish-to-start relationship in which Budget Approval is the predecessor and Prepare Samples is the successor.
The Gantt chart shows that Prepare Samples is scheduled to begin only after Budget Approval has finished. If the Budget Approval dates move, Project Insight automatically shifts Prepare Samples and any other dependent tasks.
Start-to-finish dependency example
A start-to-finish relationship means that the successor task cannot finish until the predecessor task has started. This relationship is less common, but it may be useful when one activity must remain in place until another activity begins.
The image below shows a start-to-finish relationship between the example tasks.
Can a task have more than one predecessor?
Yes. A task can have multiple predecessors when several activities must start or finish before the task can proceed.
For example, a testing task may depend on product development, test environment setup, and test data preparation. Project Insight evaluates all of the predecessor relationships when calculating the testing task's scheduled dates.
What happens when a predecessor date changes?
When a predecessor's dates, duration, or schedule changes, Project Insight's intelligent scheduling engine recalculates the connected successor tasks. Depending on the relationships in the project plan, the change may also shift tasks later in the dependency chain.
Review the Gantt chart after making scheduling changes to confirm that the resulting dates and task sequence match the intended project plan.
Predecessor scheduling best practices
- Create dependencies between individual tasks instead of summary tasks.
- Use finish-to-start unless another relationship more accurately represents the work.
- Add lead or lag time only when there is a real scheduling requirement.
- Avoid creating unnecessary dependencies that make the schedule difficult to maintain.
- Review dependency lines on the Gantt chart after changing project dates.
- Confirm that cross-project dependencies are enabled before connecting tasks from different projects.
Related information
See Adding Predecessors for more information about selecting and configuring predecessor tasks.
You can also learn more about Cross-Project Dependencies when work in one Project Insight project depends on tasks in another project.
Comments
6 comments
Hi Alex,
Are these options applicable to Start/End (Schedule) Date or Actual Start/End date?
Predecessors will change the start/end date scheduled, but not the actual dates. The actual dates are changed based on other settings to compare the schedule versus the actual. For example, the actual can be set to change based on the date a resource updates that they started and the date they update that they completed it.
Thank you Wes.
Wes, one more question.
What if we have the following option enable "Automatically Calculate Task Schedule Based on Actual Start and End Dates“
User updates the task's actual start date ahead of planned start date. Since we the option above enabled, it will update the planned start date as well, and assuming the task has lag option Finish-to-Start and its predecessor is not yet 100% completed. What will happen?
Hello Junpei,
Once the resource marks the predecessor task complete, the successor task's start date will adjust due to your "Automatically Calculate Task Schedule Based on Actual Start and End Date" settings.
This setting can delay your project plan if a task's actual end date is later than the schedule OR accelerate your project plan if a task's end date is earlier than expected.
This feature is very powerful, but it also adjusts your schedule automatically, so you have to keep a close eye on resource's updating their tasks correctly.
Thank you Margaret.
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