'Link logic' quality metric

Use this metric to check the proportion of tasks that have at least one predecessor task and at least one successor task. A high proportion of poorly-linked tasks can indicate that a schedule's link logic is faulty.

If a bar contains more than one task, a task is considered to be linked to its immediate predecessor and/or successor tasks on the bar by "implied links", even if no actual links exist between the tasks, unless the bar is configured to allow tasks to overlap. This metric treats implied links in the same way as normal links.

The start task of a project will have no predecessor tasks and the finish task will have no successor tasks. You can choose to exclude the start and finish tasks in a project from this quality metric. If the scope of a quality check is the entire project - from start to finish - it makes sense to do this, as if you include the start and finish tasks in this quality metric, they will fail the metric even though they are correctly linked. Select the Start / finish activities check box to exclude the start and finish tasks from this quality metric. If you select this check box, if there is a single task in the scope of the quality check that has no incoming links and if there is a single task in the scope that has no outgoing links, these tasks will be assumed to be the start and finish tasks and will pass the metric. If you select this check box and there are multiple tasks with only incoming or outgoing links, all such tasks will fail the metric, just as they will fail if you clear the check box.

With the Start / finish activities check box selected and the pass and fail boundaries set to 100.00%, this metric meets the requirements of CIOB stress test 1 (Logic links). With the Start / finish activities check box selected and the pass and fail boundaries set to 95.00%, this metric meets the requirements of DCMA test 1 (Logic).

You can change the impact that this metric has on the weighted total result of a quality check by entering a factor by which the quality metric should be multiplied in the Weighting field. For the weighting to have any effect, a quality check must have more than one quality metric.

Pass and fail criteria

Pass or fail?	Criteria
Pass	A project passes this metric if the percentage of tasks with at least one predecessor task and at least one successor task is greater than or equal to the pass boundary percentage.   For example, if the pass boundary was set to 95.00%, a project would pass this metric if 95.00% or more of tasks had at least one predecessor task and at least one successor task.
Fail	A project fails this metric if the percentage of tasks with at least one predecessor task and at least one successor task is less than the fail boundary percentage.   For example, if the fail boundary was set to 85.00%, a project would fail this metric if less than 85.00% of tasks had at least one predecessor task and at least one successor task.
Neither pass nor fail	If the percentage of tasks with at least one predecessor task and at least one successor task falls between the pass and fail boundary percentages, the result is neither a pass nor a fail, but somewhere in between.

Default suggested settings

• Start / finish activities: selected if the scope is the entire project; cleared if the scope is part of the project.
• Pass boundary: 95.00%. A project will pass this metric if 95.00% or more of tasks have at least one predecessor task and at least one successor task.
• Fail boundary: 85.00%. A project will fail this metric if less than 80.00% of tasks have at least one predecessor task and at least one successor task.

The following table shows whether some example projects would pass or fail this metric using these settings:

Percentage of tasks with at least one predecessor task and at least one successor task	Pass or fail?
0.00%	Fail
50.00%	Fail
84.99%	Fail
85.00%	Neither pass nor fail
85.00%	Neither pass nor fail
94.99%	Neither pass nor fail
95.00%	Pass
100.00%	Pass

Suggested settings to meet the requirements of CIOB stress test 1 (Logic links)

• Start / finish activities: selected.
• Pass boundary: 100.00%. A project will pass this metric if all tasks have at least one predecessor task and at least one successor task.
• Fail boundary: 100.00%. A project will fail this metric if any tasks do not have at least one predecessor task and at least one successor task.

The following table shows whether some example projects would pass or fail this metric using these settings:

Percentage of tasks with at least one predecessor task and at least one successor task	Pass or fail?
0.00%	Fail
50.00%	Fail
99.99%	Fail
100.00%	Pass

Suggested settings to meet the requirements of DCMA test 1 (Logic)

• Start / finish activities: selected.
• Pass boundary: 95.00%. A project will pass this metric if 95.00% or more of tasks have at least one predecessor task and at least one successor task.
• Fail boundary: 95.00%. A project will fail this metric if less than 95.00% of tasks have at least one predecessor task and at least one successor task.

The following table shows whether some example projects would pass or fail this metric using these settings:

Percentage of tasks with at least one predecessor task and at least one successor task	Pass or fail?
0.00%	Fail
50.00%	Fail
94.99%	Fail
95.00%	Pass
100.00%	Pass

Does the metric force a project to be rescheduled?

No

Suggested actions if a project fails this metric

If a project fails this metric, select the metric in the Quality Check Results dialog and click Show Failing Tasks to view the tasks that have failed the metric.

Ensure that any failing tasks are linked correctly to their predecessors and successors.

Related Topics:

Introduction to schedule quality checking

Creating relationships between tasks

Linking tasks