6.7 Control Schedule
Control Schedule is the process of monitoring the status of project activities to update project progress and manage changes to the schedule baseline to achieve the plan. The key benefit of this process is that it provides the means to recognize deviation from the plan and take corrective and preventive actions and thus minimize risk. The inputs, tools and techniques, and outputs of this process are depicted in Figure 6-22. Figure 6-23 depicts the data flow diagram of the process.
Updating the schedule model requires knowing the actual performance to date. Any change to the schedule baseline can only be approved through the Perform Integrated Change Control process (Section 4.5). Control Schedule, as a component of the Perform Integrated Change Control process, is concerned with:
- Determining the current status of the project schedule,
- Influencing the factors that create schedule changes,
- Determining if the project schedule has changed, and
- Managing the actual changes as they occur.
If any agile approach is utilized, control schedule is concerned with:
- Determining the current status of the project schedule by comparing the total amount of work delivered and accepted against the estimates of work completed for the elapsed time cycle,
- Conducting retrospective reviews (scheduled reviews to record lessons learned) for correcting processes and improving, if required,
- Reprioritizing the remaining work plan (backlog),
- Determining the rate at which the deliverables are produced, validated, and accepted (velocity) in given time per iteration (agreed work cycle duration, typically two weeks or one month),
- Determining that the project schedule has changed, and
- Managing the actual changes as they occur.
6.7.1. Control Schedule: Inputs
188.8.131.52 Project Management Plan
Described in Section 184.108.40.206. The project management plan contains the schedule management plan and the schedule baseline. The schedule management plan describes how the schedule will be managed and controlled. The schedule baseline is used as a reference to compare with actual results to determine if a change, corrective action, or preventive action is necessary.
220.127.116.11 Project Schedule
Described in Section 18.104.22.168. Project schedule refers to the most recent version with notations to indicate updates, completed activities, and started activities as of the indicated data date.
22.214.171.124 Work Performance Data
Described in Section 126.96.36.199. Work performance data refers to information about project progress such as which activities have started, their progress (e.g., actual duration, remaining duration, and physical percent complete), and which activities have finished.
188.8.131.52 Project Calendars
Described in Section 184.108.40.206. A schedule model may require more than one project calendar to allow for different work periods for some activities to calculate the schedule forecasts.
220.127.116.11 Schedule Data
Described in Section 18.104.22.168. Schedule data will be reviewed and updated in the Control Schedule process.
22.214.171.124 Organizational Process Assets
Described in Section 2.1.4. The organizational process assets that influence the Control Schedule process include, but are not limited to:
- Existing formal and informal schedule control-related policies, procedures, and guidelines;
- Schedule control tools; and
- Monitoring and reporting methods to be used.
6.7.2. Control Schedule: Tools and Techniques
126.96.36.199 Performance Reviews
Performance reviews measure, compare, and analyze schedule performance such as actual start and finish dates, percent complete, and remaining duration for work in progress. Various techniques may be used, among them:
- Trend analysis. Trend analysis examines project performance over time to determine whether performance is improving or deteriorating. Graphical analysis techniques are valuable for understanding performance to date and for comparison to future performance goals in the form of completion dates.
- Critical path method (Section 188.8.131.52). Comparing the progress along the critical path can help determine schedule status. The variance on the critical path will have a direct impact on the project end date. Evaluating the progress of activities on near critical paths can identify schedule risk.
- Critical chain method (Section 184.108.40.206). Comparing the amount of buffer remaining to the amount of buffer needed to protect the delivery date can help determine schedule status. The difference between the buffer needed and the buffer remaining can determine whether corrective action is appropriate.
- Earned value management (Section 220.127.116.11). Schedule performance measurements such as schedule variance (SV) and schedule performance index (SPI), are used to assess the magnitude of variation to the original schedule baseline. The total float and early finish variances are also essential planning components to evaluate project time performance. Important aspects of schedule control include determining the cause and degree of variance relative to the schedule baseline (Section 18.104.22.168), estimating the implications of those variances for future work to completion, and deciding whether corrective or preventive action is required. For example, a major delay on any activity not on the critical path may have little effect on the overall project schedule, while a much shorter delay on a critical or near-critical activity may require immediate action. For projects not using earned value management, similar variance analysis can be performed by comparing planned activity start or finish dates against actual start or finish dates to identify variances between the schedule baseline and actual project performance. Further analysis can be performed to determine the cause and degree of variance relative to the schedule baseline and any corrective or preventative actions needed.
22.214.171.124 Project Management Software
Project management software for scheduling provides the ability to track planned dates versus actual dates, to report variances to and progress made against the schedule baseline, and to forecast the effects of changes to the project schedule model.
126.96.36.199 Resource Optimization Techniques
Described in Section 188.8.131.52. Resource optimization techniques involve the scheduling of activities and the resources required by those activities while taking into consideration both the resource availability and the project time.
184.108.40.206 Modeling Techniques
Described in Section 220.127.116.11. Modeling techniques are used to review various scenarios guided by risk monitoring to bring the schedule model into alignment with the project management plan and approved baseline.
18.104.22.168 Leads and Lags
Adjusting leads and lags is applied during network analysis to find ways to bring project activities that are behind into alignment with the plan. For example, on a project to construct a new office building, the landscaping can be adjusted to start before the exterior work of the building is complete by increasing the lead time in the relationship. Or, a technical writing team can adjust the start of editing the draft of a large document immediately after the document is completed by eliminating or decreasing lag time.
22.214.171.124 Schedule Compression
Described in Section 126.96.36.199. Schedule compression techniques are used to find ways to bring project activities that are behind into alignment with the plan by fast tracking or crashing schedule for the remaining work.
188.8.131.52 Scheduling Tool
Schedule data is updated and compiled into the schedule model to reflect actual progress of the project and remaining work to be completed. The scheduling tool (Section 184.108.40.206) and the supporting schedule data are used in conjunction with manual methods or other project management software to perform schedule network analysis to generate an updated project schedule.
6.7.3. Control Schedule: Outputs
220.127.116.11 Work Performance Information
The calculated SV and SPI time performance indicators for WBS components, in particular the work packages and control accounts, are documented and communicated to stakeholders.
18.104.22.168 Schedule Forecasts
Schedule forecasts are estimates or predictions of conditions and events in the project's future based on information and knowledge available at the time of the forecast. Forecasts are updated and reissued based on work performance information provided as the project is executed. The information is based on the project's past performance and expected future performance, and includes earned value performance indicators that could impact the project in the future.
22.214.171.124 Change Requests
Schedule variance analysis, along with review of progress reports, results of performance measures, and modifications to the project scope or project schedule may result in change requests to the schedule baseline, scope baseline, and/or other components of the project management plan. Change requests are processed for review and disposition through the Perform Integrated Change Control process (Section 4.5). Preventive actions may include recommended changes to eliminate or reduce the probability of negative schedule variances.
126.96.36.199 Project Management Plan Updates
Elements of the project management plan that may be updated include, but are not limited to:
- Schedule baseline. Changes to the schedule baseline are incorporated in response to approved change requests (Section 188.8.131.52) related to project scope changes, activity resources, or activity duration estimates. The schedule baseline may be updated to reflect changes caused by schedule compression techniques.
- Schedule management plan. The schedule management plan may be updated to reflect a change in the way the schedule is managed.
- Cost baseline. The cost baseline may be updated to reflect approved change requests or changes caused by compression techniques.
184.108.40.206 Project Documents Updates
Project documents that may be updated include, but are not limited to:
- Schedule Data. New project schedule network diagrams may be developed to display approved remaining durations and approved modifications to the schedule. In some cases, project schedule delays can be so severe that development of a new target schedule with forecasted start and finish dates is needed to provide realistic data for directing the work, measuring performance, and measuring progress.
- Project Schedule. An updated project schedule will be generated from the schedule model populated with updated schedule data to reflect the schedule changes and manage the project.
- Risk Register. The risk register, and risk response plans within it, may also be updated based on the risks that may arise due to schedule compression techniques.
220.127.116.11 Organizational Process Assets Updates
Organizational process assets that may be updated include, but are not limited to:
- Causes of variances,
- Corrective action chosen and the reasons, and
- Other types of lessons learned from project schedule control.