What are the common causes and indicators of schedule variances and deviations?

1 Schedule variances

Schedule variances are the differences between the planned and actual schedule performance of the project, which can indicate that the project is ahead or behind schedule. Poor estimation of duration, resources, or dependencies, changes in scope, requirements, or priorities, unforeseen risks, issues, or delays, and ineffective communication, coordination, or stakeholder management are some of the common causes of these variances.

2 Schedule deviations

Schedule deviations are departures from the baseline schedule that are approved and incorporated into the project plan. They can be intentional or unintentional, resulting from change requests or errors. Common causes of schedule deviations include scope creep, gold plating, or rework; quality issues, defects, or non-conformities; changes in assumptions, constraints, or regulations; and stakeholder feedback, expectations, or satisfaction.

3 Schedule performance indicators

Schedule performance indicators are metrics used by project managers to quantify and monitor the schedule variances and deviations. These indicators can be calculated using the earned value management (EVM) method, which compares the planned value (PV), the earned value (EV), and the actual cost (AC) of the project. Common schedule performance indicators include Schedule Variance (SV) = EV - PV, Schedule Performance Index (SPI) = EV / PV, To-Complete Performance Index (TCPI) = (BAC - EV) / (EAC - AC), Estimate at Completion (EAC) = BAC / SPI, Estimate to Complete (ETC) = EAC - AC, and Variance at Completion (VAC) = BAC - EAC.

4 Schedule performance reports

Schedule performance reports are documents that present and communicate the schedule performance indicators and their analysis to the project stakeholders. These reports can vary in format, from graphical to tabular to narrative, depending on the level of detail required. Common schedule performance reports include a schedule performance dashboard, which is a visual summary of key indicators and their trends; a schedule variance analysis, which outlines causes and impacts of variances and deviations; a schedule forecast, which is a projection of future performance based on current data and assumptions; and a schedule change log, which is a record of changes made to the baseline schedule and their justification and approval.

5 Schedule performance control

Schedule performance control is the process of comparing the actual schedule performance with the planned schedule performance and taking corrective or preventive actions to align them. This includes identifying and analyzing schedule variances and deviations, evaluating alternatives and implications, and implementing changes and updates. Common tools and techniques for schedule performance control include schedule compression, which is a technique to shorten the duration of the project without compromising the scope or quality; schedule adjustment, which is a technique to modify the schedule parameters such as duration, resources, or dependencies; schedule update, which is a technique to reflect the actual progress and performance of the project in the schedule; and schedule baseline revision, which is a technique to incorporate approved changes into the baseline schedule.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?