How to Improve the Quality of your Project Schedule

The integrity of a CPM Schedule is a critical factor and important for improving the likelihood for the Project Success. But with an increasingly complex project scenarios where multitudes of activity data need to be integrated into one master baseline; how do we check the quality of our final Project Schedule? We receive multiple vendor schedules which we have been adding the integration task in our own master schedule. Broadly we rely on our experience and look for some schedule characteristics such as logical sequences of tasks, milestones, accurate dates & resource assignments to develop a schedule. Wouldn’t it help if we have a formal checklist or project schedule quality guideline? It always helps to have a formal guideline which ensures well-established correlation between the quality or soundness of a project schedule and the resulting execution performance.

Let’s dive in and take a closer look at this project schedule quality checks.

Let us categorize the Schedule Quality Analysis Metrics into the following:

·Schedule Development Quality Checks

o  Missing Logic

o  The Leads / Lags

o  Relationship Type

o  Hard Constraints

o  High Float

o  Negative Float

o  High Duration

o  Invalid Dates

o  Resources

·Schedule Management Quality Checks

o  Missed Activities

o  Critical Path Test

o  Critical Path Length Index (CPLI)

o Baseline Execution Index (BEI)

Project Schedule Quality Check#1: Missing Logic

The Missing Logic Check determines whether any activities / tasks are missing Predecessor and/or Successor. Ideally, all activities should have atleast one Predecessor and one Successor assigned to it, except the Start & Finish tasks of the project.

In actual practice we might encounter some tasks for which assigning any Predecessors or Successors may be avoided. However, it’s always good to avoid Open Ended activities in a schedule, so as to conclude on accurate Critical Path in a project.

A quality schedule should not have more than 5 percent of its tasks missing the predecessor and successor logic.

Project Schedule Quality Check#2: The Leads / Lags

Often the Scheduler uses the Lags & Leads to link between activities.

A Lag is an intentional or anticipated positive delay between the tasks. It’s supposed to hide the potential activities which otherwise can be defined separately. By minimizing the use of Lag, Critical Path calculation can be improved.

A quality schedule should have fewer than 5 percent of the tasks with lags. Instead of using a lag, we should add another task for the lag duration and during project execution, this delay can be reduced if needed.

A Lead or Negative Lag can be used to pull the task ahead of the schedule. It doesn’t carry much sense when the successor task starts earlier than the predecessor. Negative lags may just indicate the overlap of discrete work while a positive lag can be used to represent actual work. Adding Leads can negatively impact the Critical Path.

A quality schedule requires no Leads (0%)

Project Schedule Quality Check#3: Relationship Type

Among the four relationship types (Finish to Start, Finish to Finish, Start to Start & Start to Finish), 90 percent of all the tasks in the project schedule should have Finish to Start relationships. The default relationship type is a Finish to Start and it gives a flow to the schedule by providing a straight logical path to the project.

Project Schedule Quality Check#4: Hard Constraints

The schedule should be dynamic, it has to follow the logical consequences. However, in many instances a “pick a date” approach is followed. This often results in using hard constraints that indicate a task finish or start defined on specific date and not by the logic. Hard or two-way constraints such as Must Start On or Must Finish On should be avoided as they can result in a misleading schedule forecast.

For a quality Schedule, the number of activities with hard or two-way constraints should not exceed 5%

Project Schedule Quality Check#5: High Float

The schedule float is the Total Slack in Microsoft Project and Total Float in Primavera. It represents the total amount of time a task can be delayed without causing a delay to the project. Schedule paths with high amounts of float typically arise due to artificially constrained activities and/or missing relationship amongst tasks.

The threshold for the Float however depends on the type of projects and duration required for completion (e.g. large EPC projects which usually have greater time frame shall bear more floats in terms of number of days, but a typical Turnaround projects cannot afford to have high number of Days as Floats since the time is limited)

If 5% of your schedule consists of high float tasks, it's needed to review

Project Schedule Quality Check#6: Negative Float

Ideally there should not be any Negative Float in a Schedule. Negative float indicates that the schedule is not possible based on the current completion dates which is a result of artificially accelerated or constrained schedule.

Project Schedule Quality Check#7: High Duration

The Schedule Best Practice should always follow detailing to an extent so as to monitor effectively and achieve the Project Management objective. High duration activities are generally an indication that a plan is too high level for adequate planning and controls. In order to have effectively controllable Schedule for better outcomes, the High Duration Tasks needs to be decomposed further into sub-tasks. However, what extent of micro level detailing is acceptable that’s a question and it’s depends on the organizational objective.

Ideally, the project schedule should not have any high duration tasks. However, 5% is an acceptable schedule quality guideline.

Project Schedule Quality Check#8: Invalid Dates

There should not be any invalid dates in the schedule defined as activities with planned work in the past or actual work in the future indicated by all actual dates being prior to the data date and all forecast dates being on or later than this date.

Invalid Forecast Date: The invalid forecast date assumes an unfinished task cannot start or finish BEFORE the project status date. A task should have a forecast start and finish dates in the future relative to the project status date.

Invalid Actual Date: The invalid actual date check looks for tasks that have an actual start of finish date AFTER the project status date. A project schedule shouldn’t have an actual start or actual finish date in the future. All actual start and finish dates should be less than or equal to the project status date.

Project Schedule Quality Check#9: Resources

Identify the tasks which doesn’t have resource assigned. For individual tasks, resources need to be identified for proper accountability and scheduling. It is impossible to resource level a task without a resource. A high quality schedule has all resources assigned to the tasks in the schedule. Also it forms the basis for the monitoring of Project Status and Reporting.

Resource Type in Microsoft Project: Work, Material, Cost

Resource Type in Primavera: Labor, Non-Labor, Material 

Also it is important to define the attributes (e.g. Price/Unit, Calendar, Shift, Max Units/Time etc.) to the resources for Resource Management.

Project Schedule Quality Check#10: Missed Activity

The number of activities that have been completed behind the baseline completion date is a good indication of execution performance and how well (or poorly) the schedule is meeting the baseline plan. The Missed Task check helps determine how well the project schedule is performing against the baseline project schedule. The number of missed tasks should not exceed 5% of all the tasks in the project schedule. If the metric exceeds 5%, you really need to assess the reliability of the schedule and review its critical path.

This quality check is the “late finishes” check. It identifies any task that was scheduled to complete by the project status date and finished after the baseline finish date. These types of completed tasks are known late finishes. The tasks did not complete on time but they did eventually finish. The key is to ensure your forecasted schedule re-aligns to the baseline schedule as closely as possible.

Project Schedule Quality Check#11: Critical Path Test

This check evaluates the project’s network logic, particularly for the critical path and is a ‘what-if’ test performed directly on the schedule. Its intent is to identify a current critical path activity, to grossly extend its remaining duration, and note if a corresponding extension occurs to the project completion date.

Notes: Performs a test to identify broken logic or where the project completion date is NOT affected by delays in directly proportion to the amount of delay applied.

Project Schedule Quality Check#12: Critical Path Length Index

This index determines if the project finish date is realistic given the forecasted finish date. The actual formula for the critical path length index is calculated using the formula (Critical Path Length + Total Float) / (Critical Path Length). If the value is greater than 1.0, then the project finish date can be considered realistic given the forecasted finish.

Notes: The Critical Path Length Index (CPLI) is a measure of the relative efficiency required to complete a milestone on time, or how close a critical path is to the project target completion date. A project with an aggressive or conservative completion date may not carry the same overall duration as that of the critical path through the network. CPLI of greater than 1 indicates that a schedule is conservative with a very high chance of early completion. A CPLI of less than 1 is very aggressive with a very high chance that completion will overrun beyond the target project completion date.

Project Schedule Quality Check#13: Baseline Execution Index

This check you can compare to like Schedule Index EV metrics. BEI is the ratio of the number of tasks completed to the number that should have been completed by the status date. BEI should be > .95 (>1 favorable; <1 unfavorable).

It compares the number of completed tasks to the number of tasks planned to be completed by the project status date.

Additional Checks:

·        Redundant relationships: unnecessary logic in the network (also ‘link-density’ the average number of links per task)

·        Out-of-sequence progress: correction needed to logic

·        Resources on summary tasks: this may, or may not be appropriate depending on the resource.

·        Relationships on summary tasks: Should not be allowed.

Reference: DCMA 14 Point Assessment Metric