Schedule Quality Checks

Introduction

While evaluating the schedule quality, during both planning and monitoring & controlling, it is important to make assessments from a qualitative and a quantitative perspective.?A quantitative assessment of schedule quality is based on measurable criteria rooted in industry-defined scheduling best practices.

In this article, you will find a set of health checks and guidelines collectively known as the 14-Point Assessment. These are not necessarily hard and fast rules, but more indicators of potential problem areas where a deeper schedule analysis may be necessary. Here, we will examine each of the 14 points and why they are critical for a healthy project schedule.

The 14-Point only evaluates tasks in the project schedule that are valid tasks.?Summary tasks, subprojects, zero duration tasks, and formal milestone tasks are removed from the analysis.?It provides 14 different schedule quality checks as follows:

1. Logic
2. Leads
3. Lags
4. Relationship Type
5. Hard Constraints
6. High Float
7. Negative Float
8. High Duration
9. Invalid Dates
10. Resources
11. Missed Tasks
12. Critical Path
13. Critical Path Length Index (CPLI)
14. Baseline Execution Index (BEI)

1. Logic

This metric identifies incomplete tasks with missing logic links. It helps identify how well or poorly the schedule is linked together. Even if links exist, the logic still needs to be verified by the technical leads to ensure that the links make sense. Any incomplete task that is missing a predecessor and/or a successor is included in this metric. The number of tasks without predecessors and/or successors should not exceed 5%. An excess of 5% should be considered a flag.

2. Leads

This metric identifies the number of logic links with a lead (negative lag) in predecessor relationships for incomplete tasks. The critical path and any subsequent analysis can be adversely affected by using leads. The use of leads distorts the total float in the schedule and may cause resource conflicts. Per the Master Schedule (MS) Data Item Description (DID), negative time is not demonstrable and should not be encouraged. Using MS Excel, count the number of “Leads” that are found. Leads should not be used; therefore, the goal for this metric is 0.

3. Lags

This represents the number of lags in predecessor logic relationships for incomplete tasks. The critical path and any subsequent analysis can be adversely affected by using lags. Per the Master Schedule (MS) Date Item Description (DID), lag should not be used to manipulate float/slack or to restrain the schedule. Using MS Excel, count the number of “Lags” that are found. The number of relationships with lags should not exceed 5%.

4. Relationship Types

The metric provides a count of incomplete tasks containing each type of logic link. The Finish-to-Start (FS) relationship type (“once the predecessor is finished, the successor can start”) provides a logical path through the program and should account for at least 90% of the relationship types being used. The Start-to-Finish (SF) relationship type is counter-intuitive (“the successor can’t finish until the predecessor starts”) and should only be used very rarely and with detailed justification. By counting the number of Start - to-Start (SS), Finish-to-Finish (FF), and Start-to-Finish (SF) relationship types, the % of Finish-to-Start (FS) relationship types can be calculated.

5. Hard Constraints

This is a count of incomplete tasks with hard constraints in use. Using hard constraints [Must-Finish-On (MFO), Must-Start-On (MSO), Start-No-Later-Than (SNLT), & Finish-No-Later-Than (FNLT)] may prevent tasks from being moved by their dependencies and, therefore, prevent the schedule from being logic-driven. Soft constraints such as As-Soon-As-Possible (ASAP), Start-No-Earlier-Than (SNET), and Finish-No-Earlier-Than (FNET) enable the schedule to be logic-driven. Divide the total number of hard constraints by the number of incomplete tasks. The number of tasks with hard constraints should not exceed 5%. ?????????????

6. High Float

An incomplete task with a total float greater than 21 working days (1 month) is counted in this metric. A task with a total float over 21 working days may be a result of missing predecessors and/or successors. If the percentage of tasks with excessive total float exceeds 5%, the network may be unstable and may not be logic-driven.????

7. Negative Float

An incomplete task with a total float of less than 0 working days is included in this metric. It helps identify tasks that are delaying the completion of one or more milestones. Tasks with negative float should have an explanation and a corrective action plan to mitigate the negative float. Divide the total number of tasks with a negative float by the number of incomplete tasks. Ideally, there should not be any negative float in the schedule.

8. High Duration

An incomplete task with a baseline duration greater than 44 working days (2 months), and has a baseline start date within the detailed planning period or rolling wave is included in this metric. It helps to determine whether or not a task can be broken into two or more discrete tasks rather than one. In addition, it helps to make tasks more manageable; which provides better insight into cost and schedule performance. Divide the number of incomplete tasks with high duration tasks by the total number of incomplete tasks. The number of tasks with high duration should not exceed 5%.

9. Invalid Dates

Incomplete tasks that have a forecast start/finish date prior to the Master Schedule (MS) status date or have an actual start/finish date beyond the MS status date are included in this metric. A task should have forecast start and forecast finish dates in the future relative to the status date of the MS (i.e. if the MS status date is 8/1/19, the forecast date should be on or after 8/1/19). A task should not have an actual start or actual finish date that is in the future relative to the status date of the MS (i.e. if the MS status date is 8/1/19, the actual start or finish date should be on or before 8/1/19, not after 8/1/19). There should not be any invalid dates in the schedule.

10. Resources

This metric provides verification that all tasks with durations greater than zero have cost or hours assigned. Some contractors may not load their resources into the Master Schedule (MS). The (MS) (DID) may not require the contractor to load resources directly into the schedule. If the contractor does resource load their schedule, calculate the metric by dividing the number of incomplete tasks without dollars/hours assigned by the total number of incomplete tasks.????????????

11. Missed Tasks

A task is included in this metric if it is supposed to be completed already (baseline finish date on or before the status date) and the actual finish date or forecast finish date (early finish date) is after the baseline finish date or the Finish Variance (Early Finish minus Baseline Finish) is greater than zero. This metric helps identify how well or poorly the schedule is meeting the baseline plan. To calculate this metric, divide the number of missed tasks by the baseline count which does not include the number of tasks missing baseline start or finish dates. The number of missed tasks should not exceed 5%.??????????????

12. Critical Path Test

The purpose is to test the integrity of the overall network logic and, in particular, the critical path. If the project completion date (or other milestones) is not delayed in direct proportion (assuming zero float) to the amount of intentional slip that is introduced into the schedule as part of this test, then there is broken logic somewhere in the network. Broken logic is the result of missing predecessors and/or successors on tasks where they are needed. The (MS) passes the Critical Path Test if the project completion date (or other tasks/milestone) shows a negative total float number or a revised Early Finish date that is in direct proportion (assuming zero float) to the amount of intentional slip applied.

13. Critical Path Length Index (CPLI)

The Critical Path Length Index (CPLI) is a measure of the efficiency required to complete a milestone on time. It measures critical path “realism” relative to the baselined finish date when constrained. A CPLI of 1.00 means that the program must accomplish one day’s worth of work for every day that passes. A CPLI of less than 1.00 means that the program schedule is inefficient with regard to meeting the baseline date of the milestone (i.e. going to finish late). A CPLI greater than 1.00 means the program is running efficiently with regard to meeting the baseline date of the milestone (i.e. going to finish early). The CPLI is an indicator of efficiency relating to tasks on a milestone’s critical path (not to other tasks within the schedule). The CPLI is a measure of the relative achievability of the critical path. A CPLI less than 0.95 should be considered a flag and requires further investigation.

The CPLI requires determining the program schedule’s Critical Path Length (CPL) and the Total Float (TF). The CPL is the length of workdays from a time now until the next program milestone that is being measured. TF is the number of days a project can be delayed before delaying the project completion date. TF can be negative, which reflects that the program is behind schedule. The mathematical calculation of total float is generally accepted to be the difference between the “late finish” date and the “early finish” date (late finish minus early finish equals total float).??????????

14. Baseline Execution Index (BEI)

The Final metric, Baseline Execution Index (BEI) is an MS-based metric that calculates the efficiency with which tasks have been accomplished when measured against the baseline tasks. In other words, it is a measure of task throughput. The BEI provides insight into the realism of program cost, resource, and schedule estimates. It compares the cumulative number of tasks completed to the cumulative number of tasks with a baseline finish date on or before the current reporting period. It measures the throughput with which the project team is accomplishing tasks. It is calculated by dividing the total number of tasks completed by the total number of tasks baselined to have been completed as of the project status date. A BEI of 1.00 indicates the project team is executing on the plan, with greater than 1.00 indicating ahead of schedule and below 1.00 indicating behind schedule. A BEI below 0.95 to be indicative of a potential issue requiring further investigation.

Conclusion

The 14-Point Assessment offers the program/project manager a great way to objectively evaluate schedule quality over the life of the project. While satisfying these guidelines doesn’t necessarily mean the schedule is feasible, not satisfying them almost certainly means it is not. It would be in the best interest of all project managers to routinely perform this assessment to maximize the likelihood of on-time project performance.

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