In project management, variance represents the difference between what was planned and what actually occurred. Cost variance, in particular, highlights whether a project is spending more or less than expected and often triggers corrective actions when deviations become significant.
Key Terms at Time Now
Ei — Initial Estimate The planned or estimated budget at the start of the project.
A — Actuals The actual cost incurred to date.
E(t‑c) — Estimate‑to‑Complete The expected cost required to finish the remaining work.
E(a‑c) — Estimate‑at‑Completion The updated forecast of total project cost:
V(a‑c) — Variance‑at‑Completion The difference between the original estimate and the updated forecast:
Adjusting the Estimate at a Future Time (Time Now + T)
If, at a later point in the project, the variance becomes too large—indicating excessive error, drift, or cost discrepancy—then the project manager may decide to reset the baseline.
In that case:
This establishes a more realistic baseline for future tracking and improves the accuracy of ongoing performance measurement.
