A 2x2 classification of stakeholders by their authority over the project and their interest in its outcome, producing a differentiated engagement strategy for each quadrant.

When to use: During initiating and planning, whenever a new senior stakeholder appears, and before any major change request or escalation.

Risk Probability-Impact Matrix

A scoring grid that ranks identified risks by likelihood and consequence so that limited response effort goes to the risks that actually threaten objectives.

When to use: In qualitative risk analysis, right after risk identification, and at every risk review during execution.

Work Breakdown Structure (WBS)

A deliverable-oriented hierarchical decomposition of the total project scope into work packages small enough to estimate, assign and control.

When to use: In scope planning, before schedule and cost estimating — every activity, estimate and control account derives from it.

Critical Path Method (CPM)

A network analysis technique that computes the longest path of dependent activities to determine the shortest possible project duration and the float available on every other path.

When to use: Whenever the schedule must be committed, compressed or recovered, and to judge the true schedule impact of any delay or change request.

Formulas library

Every formula with variables, interpretation thresholds and a worked example.

Cost Performance Index

CPI = EV / AC

EV: Earned Value (USD)
AC: Actual Cost (USD)

CPI > 1.0 — Under budget
CPI = 1.0 — On budget
CPI < 1.0 — Over budget

Worked example

An office fit-out has a $400,000 budget. At the end of month 3 the team has completed 45% of the planned scope and spent $210,000.

CPI = 180,000 / 210,000 = 0.857

The project earns only 86 cents of value per dollar spent — roughly 14% cost overrun if the trend holds.

Try: An office fit-out has a $400,000 budget.

Schedule Performance Index

SPI = EV / PV

EV: Earned Value (USD)
PV: Planned Value (USD)

SPI > 1.0 — Ahead of schedule
SPI = 1.0 — On schedule
SPI < 1.0 — Behind schedule

Worked example

A software rollout planned $250,000 of work by week 10 but has earned $220,000 of value.

SPI = 220,000 / 250,000 = 0.88

The team is delivering at 88% of planned pace — about 1.2 weeks behind after 10 weeks.

Try: A software rollout planned $250,000 of work by week 10 but has earned $220,000 of value.

Cost Variance

CV = EV - AC

EV: Earned Value (USD)
AC: Actual Cost (USD)

CV > 0 — Under budget
CV = 0 — On budget
CV < 0 — Over budget

Worked example

Same office fit-out: EV $180,000 against AC $210,000.

CV = 180,000 - 210,000 = -30,000

The project is $30,000 over budget for the work completed so far.

Try: Same office fit-out: EV $180,000 against AC $210,000.

Schedule Variance

SV = EV - PV

EV: Earned Value (USD)
PV: Planned Value (USD)

SV > 0 — Ahead of schedule
SV = 0 — On schedule
SV < 0 — Behind schedule

Worked example

Software rollout: EV $220,000 against PV $250,000 at week 10.

SV = 220,000 - 250,000 = -30,000

$30,000 worth of planned work has not been delivered yet.

Try: Software rollout: EV $220,000 against PV $250,000 at week 10.

Estimate at Completion (CPI method)

EAC = BAC / CPI

BAC: Budget at Completion (USD)
CPI: Cost Performance Index (index)

EAC > BAC — Forecast overrun
EAC = BAC — On plan
EAC < BAC — Forecast underrun

Worked example

Office fit-out with BAC $400,000 running at CPI 0.86.

EAC = 400,000 / 0.857 = 466,744

Expect roughly $67,000 of overrun unless cost efficiency improves.

Try: Office fit-out with BAC $400,000 running at CPI 0.

Estimate to Complete

ETC = EAC - AC

EAC: Estimate at Completion (USD)
AC: Actual Cost to date (USD)

ETC > remaining budget (BAC - AC) — Additional funds needed
ETC <= remaining budget — Fundable from baseline

Worked example

Office fit-out: EAC $466,700 with $210,000 already spent.

ETC = 466,700 - 210,000 = 256,700

$256,700 more is needed, versus $190,000 of budget remaining — a $66,700 funding gap.

Try: Office fit-out: EAC $466,700 with $210,000 already spent.

Variance at Completion

VAC = BAC - EAC

BAC: Budget at Completion (USD)
EAC: Estimate at Completion (USD)

VAC > 0 — Forecast saving
VAC = 0 — On budget
VAC < 0 — Forecast overrun

Worked example

Office fit-out: BAC $400,000, EAC $466,700.

VAC = 400,000 - 466,700 = -66,700

Raise a change request for roughly $67,000 or cut scope now.

Try: Office fit-out: BAC $400,000, EAC $466,700.

To-Complete Performance Index

TCPI = (BAC - EV) / (BAC - AC)

BAC: Budget at Completion (USD)
EV: Earned Value (USD)
AC: Actual Cost (USD)

TCPI < 1.0 — Achievable
TCPI = 1.0 — Exactly on plan
TCPI > 1.0 — Hard to achieve

Worked example

Office fit-out: BAC $400,000, EV $180,000, AC $210,000.

TCPI = (400,000 - 180,000) / (400,000 - 210,000) = 220,000 / 190,000 = 1.158

The team must work 16% more cost-efficiently than planned for the rest of the project — unlikely at CPI 0.86.

Try: Office fit-out: BAC $400,000, EV $180,000, AC $210,000.

PERT Three-Point Estimate (Beta)

E = (O + 4M + P) / 6

O: Optimistic duration or cost (days)
M: Most likely duration or cost (days)
P: Pessimistic duration or cost (days)

E close to M — Balanced risk
E noticeably > M — Downside-heavy
E noticeably < M — Upside-heavy

Worked example

A data-migration task is estimated at 8 days optimistic, 12 days most likely, 26 days pessimistic.

E = (8 + 4x12 + 26) / 6 = 82 / 6 = 13.67

Plan 14 days, not 12 — the long tail adds nearly two days of expected duration.

Try: A data-migration task is estimated at 8 days optimistic, 12 days most likely, 26 days pessimistic.

PERT Standard Deviation

SD = (P - O) / 6

P: Pessimistic estimate (days)
O: Optimistic estimate (days)

SD small relative to E (< 10%) — Tight estimate
SD 10-25% of E — Moderate uncertainty
SD > 25% of E — High uncertainty

Worked example

Same data-migration task: O = 8 days, P = 26 days, E = 13.7 days.

SD = (26 - 8) / 6 = 3.0

There is ~95% confidence the task lands between 7.7 and 19.7 days (E ± 2 SD) — commit to 20 days externally.

Try: Same data-migration task: O = 8 days, P = 26 days, E = 13.

Communication Channels

Channels = n(n - 1) / 2

n: Number of stakeholders in the communication network (people)

Up to ~15 channels — Informal works
15-60 channels — Needs structure
Over 60 channels — Communication overhead risk

Worked example

A steering group has 9 members and two new directors join.

Before: 9x8/2 = 36. After: 11x10/2 = 55.

Adding two people adds 19 communication paths — formalise the reporting structure.

Try: A steering group has 9 members and two new directors join.

Total Float (Slack)

TF = LS - ES = LF - EF

LS: Late Start (day)
ES: Early Start (day)
LF: Late Finish (day)
EF: Early Finish (day)

TF = 0 — Critical activity
TF > 0 — Has slack
TF < 0 — Negative float

Worked example

Activity D on a non-critical path: ES day 12, EF day 17, LS day 19, LF day 24.

TF = 19 - 12 = 7 (and 24 - 17 = 7)

Activity D can slip up to 7 days before it becomes critical — a safe place to borrow resources from.

Try: Activity D on a non-critical path: ES day 12, EF day 17, LS day 19, LF day 24.