Which snack should get the shelf space?
Decide whether a new snack earns more for the category.
The question
You advise a fictional UK convenience retailer. Replacing the only facing for the current snack removes it and all its sales. All store costs and trading terms stay fixed.
| Units sold | Retailer contribution per unit (£) | |
|---|---|---|
| Current snack | 36 | 0.6 |
| Proposed snack (forecast) | 30 | 0.9 |
One facing is available. The retailer wants to increase total category contribution.
“Would you replace the current snack? Account for purchases that move between items.”
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A strong answer, step by step
Open each step in turn. This is one strong answer, not the only one.
Step 1: Whose result should decide the swap?
What would you do here? Open the move you’d make.
Use the supplier’s sales for the proposed snack.
Tempting, but it misses something. The retailer needs its own contribution across the shelf.
Use total retailer category contribution.
The strong move. This captures the item that leaves and any other displaced purchases.
Use the higher contribution per unit.
Tempting, but it misses something. A larger margin per unit can still produce a lower total.
See how a strong candidate says it
“Use the retailer’s contribution across the snack category. The decision affects the removed item and can also affect other items still on the shelf.”
Why it works: The retailer needs the result for the category that uses the shelf space.
Step 2: What does the forecast show?
What would you do here? Open the move you’d make.
Estimate a £5.40 gain on the facing and check the rest of the category.
The strong move. This distinguishes the first calculation from the final decision.
Claim £27.00 in extra category contribution.
Tempting, but it misses something. The retailer gives up the £21.60 it earns from the current facing.
Reject the swap because the new item sells six fewer units.
Tempting, but it misses something. The unit count alone does not establish contribution.
See how a strong candidate says it
“The current facing earns £21.60. The forecast for the proposed facing is £27.00, a £5.40 gain before changes elsewhere in the category.”
Why it works: The forecast covers the facing. Ask what shoppers would have bought without the proposed snack.
Step 3: Does the pilot change the result?
The pilot confirms 30 new units per store per week. Of these, 12 replace purchases of another snack that stays on the shelf and earns £0.70 per unit. That loss is in addition to the 36 sales of the removed snack. All other sales stay the same.
What would you do here? Open the move you’d make.
Keep the £5.40 gain because the other snack stays on the shelf.
Tempting, but it misses something. A stocked item can still lose sales to the new one.
Subtract the £8.40 loss on the retained snack.
The strong move. This gives a £3.00 loss across the category.
Value the 12 displaced sales at £0.90 each.
Tempting, but it misses something. The lost units were from the snack that earns £0.70 each.
See how a strong candidate says it
“The other snack loses £8.40. The new facing’s £5.40 gain becomes a £3.00 loss for the category per store per week.”
Why it works: The new facing earns its full contribution. The retailer gives up contribution on the removed and displaced units.
Step 4: What shelf change would you approve?
What would you do here? Open the move you’d make.
Replace the facing because the new snack earns more on that row.
Tempting, but it misses something. The rest of the category loses more than the facing gains.
Test a different placement and record only the new item’s sales.
Tempting, but it misses something. That repeats the missing category check.
Keep the facing and use total category contribution in any new test.
The strong move. This protects the retailer’s stated objective.
See how a strong candidate says it
“Keep the current facing. If another placement is possible, test what the new snack adds after the retailer accounts for the sales it displaces.”
Why it works: The tested replacement reduces weekly category contribution.
The answer, in short
- Decision
- Keep the current facing under the tested conditions.
- Because
- Losses on the other snack exceed the new facing’s gain.
- What would change it
- Evidence that a different placement adds more than it displaces.
Common traps
- Counting new item contribution alone.
- Using the new item margin for the lost purchases.
Check your answer
- Whose contribution matters?
- What does the facing gain?
- Which sales moved from a retained item?
- What result would justify another placement?
Last reviewed Nov 11, 2026