Overview
Schedule variance (SV) measures how closely a project's actual progress aligns with its planned timeline. It represents the difference between the value of work completed and the value of work scheduled to be completed by a specific date.
SV = EV - PV
or
SV = BCWP - BCWS
Where:
- EV (Earned Value): Sum of all budgeted costs of completed work
- PV (Planned Value): Budgeted cost of planned tasks
- BCWP: Budgeted Cost of Work Performed
- BCWS: Budgeted Cost of Work Scheduled
Interpreting Results
Positive Schedule Variance (SV > 0)
- Project is ahead of schedule
- Completed more work than planned
- Good indicator of project health
Zero Schedule Variance (SV = 0)
- Project is exactly on schedule
- Work completed matches plan
- Ideal situation
Negative Schedule Variance (SV < 0)
- Project is behind schedule
- Less work completed than planned
- Requires corrective action
Duration Variance
Related metric from Microsoft Project:
Duration Variance = Duration - Baseline Duration
- Negative number: Task taking less time than originally planned
- Positive number: Task taking more time than planned
- Zero: Task taking exactly as much time as planned
Benefits
- Identifies deviations from planned schedule
- Enables early corrective actions
- Provides objective performance measure
- Supports data-driven decision making
- Facilitates stakeholder communication
- Helps predict project completion date
Best Practices
- Calculate variance regularly (weekly or bi-weekly)
- Analyze trends over time, not just single points
- Investigate root causes of variances
- Take corrective action promptly
- Update project plans based on learnings
- Communicate variances to stakeholders
Integration with Time Tracking
- Time tracking provides actual hours worked (basis for EV)
- Planned time provides PV baseline
- Comparison reveals schedule performance
- Supports accurate forecasting
- Identifies underperforming tasks or resources
- Cost Variance (CV): EV - AC
- Schedule Performance Index (SPI): EV / PV
- Cost Performance Index (CPI): EV / AC
- Estimate at Completion (EAC): Forecasted final cost
- Estimate to Complete (ETC): Cost to finish remaining work
