name: estimation
description: A lightweight fixed-cost scoping / estimation discipline that de-risks fixed-cost bids — a CHECKLIST + METHOD, not a heavy model. Produces a work breakdown plus PERT-weighted effort estimates, uncertainty ranges, assumptions & exclusions, and contingency, feeding the SoW scope boundary. PERT (three-point: optimistic / most-likely / pessimistic) is the default technique; analogous, parametric, and bottom-up are alternatives. Gantt charts / scheduling are rendered in EXTERNAL tools (Smartsheet, MS Project) from the work breakdown — this skill produces the breakdown + estimates, not the chart. It OWNS the estimation/scoping discipline; it DELEGATES the proposal/SoW wrapper to proposal-writing, the build breakdown to epic-planning, and sequencing to decision-package. Triggers — "estimate this engagement", "PERT estimate", "fixed-cost scoping", "work breakdown for estimation", "contingency / uncertainty range". Independently triggerable; also the pricing step of the proposal-writing flow.
license: Apache 2.0
metadata:
category: consulting
Estimation
Provisional pending the first-engagement gate. This wiring is the floor, not the finished standard;
refine it after the first real paid engagement is estimated and delivered against.
Overview
A fixed-cost scoping / estimation discipline that de-risks fixed-cost bids. It is deliberately
light — a checklist plus a method, not a model. The job is to turn an engagement into a
defensible number: a work breakdown, PERT-weighted effort with uncertainty ranges,
explicit assumptions & exclusions, and contingency — then hand those to the SoW so the price
and the scope boundary rest on the same evidence.
It is independently triggerable (any "estimate this" / "PERT estimate" request) and is also the
pricing step of the proposal-writing flow.
It composes by reference: the estimate decomposes against the build breakdown owned by
epic-planning, and its sequencing/roadmap framing comes
from decision-package. It restates neither.
What it covers (R4)
- Decomposition (work breakdown). Break the engagement into estimable leaf items — small enough
that each can carry a three-point estimate. For build-tier work, decompose against the EPIC/PLAN
breakdown from
epic-planning; do not invent a parallel
breakdown.
- Uncertainty ranges. Each leaf gets a range, not a point. PERT (below) is how the range becomes
a weighted estimate plus a variance you can roll up.
- Assumptions & exclusions. State what the number assumes (inputs, access, decisions,
availability) and what it explicitly excludes. The exclusions are the SoW out-of-scope list —
one list, two documents (see
proposal-writing).
- Contingency. A buffer sized from the rolled-up variance and the assumption risk — not a flat
guess. The worksheet shows the roll-up.
- Link to the SoW scope boundary. The breakdown's leaves are the in-scope items; the exclusions
are the out-of-scope items; the PERT total + contingency is the fixed-frame price.
Techniques: PERT is the default
Multiple estimation techniques exist; PERT is the favoured system here because three-point
estimates make fixed-cost uncertainty explicit and roll up into a defensible contingency.
PERT (three-point) — the default. For each leaf, capture three estimates and weight them:
Expected (TE) = (O + 4·M + P) / 6 SD = (P − O) / 6 Variance = SD²
- O = optimistic (everything goes right), M = most-likely, P = pessimistic (plausible
worst case — not catastrophe).
- Roll up: engagement TE = Σ leaf TE; engagement SD = √(Σ leaf variances).
- Size contingency from the rolled-up SD (e.g. a one- or two-SD buffer for the confidence level
the fixed frame needs). The worksheet does the arithmetic.
Alternatives (use when they fit better, or to triangulate):
| Technique | Use when |
|---|
| Analogous (top-down, from a similar past engagement) | Early, little detail; a quick sanity anchor |
| Parametric (units × rate, e.g. per source system / per ontology module) | The work scales with a countable driver |
| Bottom-up (sum of leaf estimates) | Detail exists; pairs naturally with PERT per leaf |
Triangulate when the stakes are high: a PERT bottom-up that disagrees with an analogous top-down is a
signal to re-examine the breakdown.
Gantt / scheduling is EXTERNAL
This skill produces the work breakdown + estimates. It does not draw Gantt charts or
schedules. Scheduling (dependencies, calendar, resource levelling, the Gantt itself) is rendered in
external tools — Smartsheet or MS Project — by importing the work breakdown. Do not attempt to
draw Gantts in-repo; produce a clean breakdown that those tools can consume. Sequencing intent
(pilot → scale order) comes from decision-package; the calendar
rendering of it is the external tool's job.
The checklist
Run before any number leaves the room:
The fillable worksheet (PERT table + roll-up + contingency) is in
references/pert-worksheet.md; the full checklist is in
references/estimation-checklist.md.
Boundary & Related Skills
This skill OWNS: the estimation / scoping discipline — PERT + work breakdown + uncertainty
ranges + assumptions/exclusions + contingency, and the clean breakdown that external scheduling tools
consume.
This skill DELEGATES:
- The proposal / SoW wrapper (and the scope-boundary discipline the exclusions feed) →
proposal-writing.
- The build breakdown the estimate decomposes against →
epic-planning.
- Sequencing / roadmap intent (pilot → scale) →
decision-package.
- The calendar/Gantt rendering → external tools (Smartsheet, MS Project) — out of repo.
Related: proposal-writing, epic-planning, decision-package.
Tone & style
British English. Terse and numeric. Every number traces to a leaf, an assumption, and a technique; no
unexplained round figures. A point estimate without a range is a smell — show the range and the
contingency that covers it.
