evm

EVM: Earned Value Management for Project Health Tracking

Source: github.com/lemur47/logic

Purpose

Help users answer one question: "Are we on track?" using Earned Value Management metrics. This skill replaces gut-feel status reporting and traffic-light dashboards with four computed numbers (SV, SPI, CV, CPI) that tell you exactly where a project stands — in schedule and in budget — at any point in time.

EVM is the performance counterpart to PERT. PERT asks "how long will it take?" before the project starts. EVM asks "are we on track?" once it's running.

When to Use

• Mid-project health checks ("we're 3 months in, are we OK?")
• Sponsor/steering committee reporting with actual data
• Detecting schedule or cost problems before they become crises
• Evaluating whether 人海戦術 (adding headcount) is helping or hurting
• Deciding whether to re-baseline, descope, or extend the deadline
• Any situation where someone says "I think we're roughly on track"

Terminology — The 4 Inputs

EVM has four inputs. Everything else is computed. Never confuse input with output.

Abbr	Full Name	What It Means	Who Provides It
BAC	Budget at Completion	Total planned budget for the entire project	Set once at baseline, frozen
PV	Planned Value	How much work should be done by now, in budget terms	Derived from schedule: BAC × (% of schedule elapsed)
EV	Earned Value	How much work is actually done, valued at planned rates	Sum of (planned cost of each completed deliverable × its % complete)
AC	Actual Cost	What was actually spent on the work performed	From accounting, timesheets, or invoices

Critical distinction: EV is not what was spent. EV is the planned budget for the work that's been completed. If a $10,000 deliverable is 50% done, EV = $5,000 regardless of whether you actually spent $3,000 or $8,000 on it.

PV shortcut (linear assumption): If you don't have a detailed planned-value curve, use: PV = BAC × (months elapsed / total months). This assumes work is evenly distributed — good enough for most conversational health checks.