Product Definition · master area
Slicing & Prioritization
Which stories ship together, in what order. Value-driven, not effort-driven. Required-for-prediction stories must all be in the slice — or the slice can't test what it claims.
Owners: PO, Trio Phase it lives in: What We Build (Volume III) The corpus principle this enacts: Predictions over plans.
Where it lives in the chain
- What We Build · Walking Skeleton replaces MoSCoW — why slicing is by value, not by must/should/could
- What We Build · Splitting & merging — the operational mechanics
How to do this
The PO slices the story map into releases by asking, in order:
- What is the prediction this slice tests? "Slice 1 tests whether the shortcut moves the grading time from 47 min to under 25 min — the partial step before the full target."
- Which stories are required for that prediction to be testable? "Stories A, C, E, G are required. The shortcut needs to work, the next-exam navigation needs to work, the rollback needs to work. Without all four, the test is invalid."
- What can be deferred to the next slice without invalidating the test? "Stories B, D, F can wait — they add convenience but the prediction still tests without them."
- What's the smallest possible thing that still proves something? "This is slice 1. It's smaller than we'd like to ship. That's the point."
What good practice looks like
A team slicing the grading-shortcut Epic:
| Slice | Predicts | Required stories | Deferred |
|---|---|---|---|
| 1 — shortcut MVP | Shortcut reduces session to under 25 min | Open, shortcut-key, next-exam, basic state preservation | Undo, multi-section, statistics view |
| 2 — full prediction | Session under 15 min | Add undo, performance optimisation | Multi-section, statistics |
| 3 — broader rollout | Sustained at scale | Multi-section, batch operations | Statistics |
| 4 — extras | Power-user adoption | Statistics view, customisation | — |
Each slice is a thing the team can ship, a thing the named person can use, and a thing the prediction can test against. Three properties that, together, define what a slice is.
The MoSCoW alternative — Must / Should / Could / Won't — produces a feature list with vague priorities. Walking-skeleton slicing produces a list of things you can ship in order, each one testing a sharper version of the prediction.
Related crafts
- Walking Skeleton — what slice 1 looks like
- Story Mapping — the picture slicing draws horizontal lines through
- Epic Naming & Kickoff — where slicing starts to take shape