Replenish
What should we send each store this week, and by which size?
The size-level demand planner I built for a footwear retailer. It replaced a spreadsheet only I could run, and the stores plan every week in it now. The engine proposes a number for every size in every store and calls for human judgement where it matters most.
You can't stock every size, and you can't afford to miss the sale.
Sales are less predictable than they seem.
With 18 possible sizes, you’re unlikely to see sales fall in a perfect curve. Online a shopper picks 13. In the store the same shopper buys 12.5.
The tail is rare, and it is not never.
<1.6% chance of selling sizes 14–16. If a style sells 30 times in a month, there is still about a 50% chance one of those three sizes sells.
Demand curveOne month, actual
The stockroom is finite.
If we order the same amount for everything, we don’t stock breadth.
20
Equal allocation
37
Demand-weighted
Missing the size gets expensive.
40%of an intended sale can be lost.1
You can’t stock too much of one model. That sacrifices units you could stock another in, and someone might walk forever.
1 Gruen & Corsten, 2007. Grocery and consumer goods; not footwear-specific. Source
Step 1: Each category is assigned a demand curve
Algorithm defines the curve - Judgement refines it.
The demand curve
Store, 365 days E-com, 365 days The demand curve
Store weight0 / 100
Smoothing0
Step 2. The curve is turned into tiers - which become the allocation rules
A planner assigns tiers based on merchandising decisions.
The six knobs behind a tier
Every tier in the strategy lab is these same six numbers. Tier 3’s own values are shown as the example.
See the tiers in action
Walk through the week in the planning grid.
The engine proposes a Suggested Target for every size. The planner decides.
Chelsea Boot
Men’s Boots · Harbor · Tier 3
| When | Assortment tier | OH | 30D | Target | TO | Decision |
|---|---|---|---|---|---|---|
| Jul 27 | 2 | 26 | 31 | 29 | 14 | Suggested |
| Aug 3 | 2 | 31 | 24 | 28 | hold | Keep |
| Aug 10 | 3 | 24 | 19 | 21 | hold | Keep |
| Aug 17 | 3 | 16 | 38 | 23 | 9 | Override |
| Aug 24 (this week) | 3 | 20 | 46 | 37 | open | Suggested |
Send the week for review.
The planner goes through the granular details. The reviewer receives the information they need to approve orders.
What else it does.
Sales analytics
Category and size performance behind the plan, on a longer window than the week.
Returning to the warehouse
Sizes a store will not sell, called back to the warehouse.
Transfers between stores
One store is long in a size another store is short in, so the units move sideways.