This document outlines a process for structuring story slicing using a grocery shopping example. It describes breaking down an epic user story into more detailed slices by considering the user role, their actions, relevant data objects and states, possible displays, non-functional requirements, and business rules. The example slices the epic "As a user I want to buy some food online" by first considering the user role as a frequent buyer performing the action of paying for milk, with acceptance criteria focused only on payment processing and without addressing other story elements like finding or adding the product to the cart.

1. Structured Story Slicing
A Grocery example
Simple illustration of the pattern outlined by
Ellen Gottesdiener & Mary Gorman
More detail :
http://www.ebgconsulting.com/Pubs/Articles/SlicingRequirementsForAgileSucc
ess_Gottesdiener-Gorman_August2010.pdf

2. A story that is too big..
As a user
I want to buy some food online
so that I don’t need to go to the shops to get it

3. User role
Action
Object
Display
Non functional
Business rules
Slicing options
Follow this structure step-by-step to slice and Epic into a
story that is small enough to be completed within days

4. 1: User Role Options
• Who acts in the user role?
– Frequent buyer
– Club card member
– Corporate buyer
– Anonymous user
• What are the states of that role?
– New, existing, lapsed, blocked, anonymous

5. 2: Action options
• What actions are needed to meet the user’s
goal?
– Verify product cost
– Calculate tax amount
– Calculate total purchase amount
– Apply discount
– Secure payment
– Adjust inventory
– Confirm receipt

6. 3: Data object options: Types / states
• What data objects are acted upon?
• What are the states of those data objects?
Product type options Payment Options Receipt type Options
Milk
Beer
Live carp
Gift card
Cash at the door
Credit card
Debit card
PayPal
Cheque
Purchase order
On screen
Credit card receipt
Emailed receipt
VAT receipt

7. So the first slice might be..
• As a frequent buyer I want to pay for a carton
of milk
• Acceptance criteria
– Use Visa debit card
– Confirmation shown on screen
Note: previous stories may exist to cover; find milk, add to
basket etc. Or these might have been ‘stubbed’

8. 4: Display options
• A plain screen with just the fields for the story
• Use the existing look and feel
• New improved look

9. 5: Non-functional options
• Response times <5 ms
• Target time <.05 ms

10. 6: Business rule options
• What business rules must be enforced for the
actions and data objects?
– Don’t validate payments of less than £50
– Include VAT in payment calculation
– Show milk as available

11. First slice continued..
As a frequent buyer I want to pay for a carton of
milk
• Acceptance criteria
– Use Visa debit card (no validation on amount)
– Confirmation shown on screen (no formatting)
– VAT is included in price and shown
– Use the existing UI
– Performance does not matter