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Inventory Forecasting: Why Historical Sales Alone Aren't Enough
Last year’s sales show what left the store, not everything customers wanted. In Merchmix Core, connect that history with availability, seasonal assumptions and the stock already committed before deciding what to buy.
INSIDE MERCHMIX / CORE
Read the history.
See the context.
Follow a coat forecast through the MFP/WSSI grid. Compare historical sales with a seasonal outlook, then trace its effect on weekly stock.
Weekly planning illustration based on the Merchmix MFP/WSSI screen.
MFP/WSSI
Working outlookSales, stock and intake in one weekly plan.
Medium unavailable in the three historical weeks. Ten sales a week is an incomplete demand signal.
Select outerwear and the coming three weeks. Compare unit measures on the same basis.
THE KEY IDEA
Use Core’s MFP/WSSI to connect the demand assumption with availability, weekly stock and incoming supply. In this example, sixty forecast sales and seventy available units leave ten, so a stronger outlook does not automatically mean another order.
Ten sales a week does not always mean ten units of demand
A coat records ten sales a week for three weeks. Copy that pattern into the next plan and the forecast becomes thirty units. But the main size was unavailable throughout those weeks. The sales record reflects a constraint as well as customer demand.
Merchmix is a connected platform for retail planning and operations. Core is its planning product. In Core, MFP/WSSI brings weekly sales, stock, intake and financial assumptions into one planning workspace, so the next buying decision can account for more than the sales history.
Check what customers could actually buy
The ten recorded sales are evidence; they are not a measure of the demand lost while medium was unavailable. Check size availability, the period affected and recent trading before setting a new expectation. Do not simply double the history to compensate for a shortage.
For the worked example, the planner proposes fifteen, twenty and twenty-five coat sales across the coming three weeks. That sixty-unit outlook assumes a seasonal build. It is a planning assumption to test, not a claim that last year’s missing sales have been calculated.
AN APPAREL PLANNING SCENARIO
A low sales history can hide unavailable sizes
Last year recorded ten coat sales in each of three weeks while medium was unavailable. The proposed seasonal outlook is fifteen, twenty and twenty-five. With fifty units on hand and twenty due in week two, projected closing stock is thirty-five, thirty-five and ten. The forecast remains an assumption, and the receipt is assumed to arrive before week-two sales.
Illustrative situation, not a customer case study.Keep seasonal timing visible in MFP/WSSI
Sixty units spread evenly across three weeks gives a different stock requirement from a rising fifteen, twenty and twenty-five. A total hides the week in which demand becomes strongest. Compare the seasonal calendar, promotional activity and recent sales before choosing the shape.
The MFP/WSSI screen provides period controls including Week and Month, a metric search and trend lines beside the rows. Use the weekly view to keep the proposed selling pattern visible. In the animation, the selected scope is Outerwear / Everyday Coat and all quantities are units.
Bring current stock into the forecast decision
The coat starts with fifty units on hand. Under the copied ten-unit weekly forecast, closing stock would be forty, fifty and forty once the twenty-unit receipt in week two is included. That projection makes the range appear more heavily stocked than the proposed seasonal outlook does.
With sales of fifteen, twenty and twenty-five, projected closing stock becomes thirty-five, thirty-five and ten. The calculation is opening stock plus intake minus sales, carried forward each week. The same supply supports two very different closing positions because the demand assumption changed.
Count the incoming order before proposing another buy
Twenty units are already due in week two. The example assumes they arrive before that week’s sales. Fifty opening units plus twenty incoming units gives seventy available over the horizon; subtract sixty forecast sales and ten remain.
A higher forecast therefore does not, on these assumptions alone, justify a new order. An extra twenty-unit buy would leave thirty rather than ten. Check required cover, size availability and the delivery date before changing the commitment. If the receipt arrives late, the weekly closing totals need a timing check as well.
FROM THE SIGNAL TO THE MERCHMIX DECISION
What to check before the next action
| What you see | Where to look in Merchmix | The decision to review |
|---|---|---|
| 10 recorded sales each week; medium unavailable | Historical sales and availability context | Do not treat constrained sales as a complete demand measure. |
| Proposed forecast: 15, 20 and 25 units | Core / MFP/WSSI weekly forecast | Test the seasonal build against recent trading and the calendar. |
| 50 held + 20 due − 60 sales = 10 closing | Weekly intake and stock projection | Check timing and sizes before proposing another order. |
Compare the measures without mixing their meaning
The MFP/WSSI grid places historical, budget and forecast measures across the planning periods, with trend lines alongside them. In the article animation, MD_SALES_LY_U represents last-year sales units and FP_SALES_FC_U represents forecast sales units. Incoming supply and projected closing stock are shown with plain labels.
Keep the merchandise scope, period and unit basis consistent. A value measure cannot be compared directly with a unit requirement. A historical sales row is also not an instruction to copy the same figure into every future forecast cell.
The proposed 60 sales use 50 held and 20 due, leaving 10 at the horizon.
Explore MFP/WSSIAsk Yukti to explain the stock effect of the forecast
Yukti is Merchmix’s assistant for investigating a planning question and preparing a supported next step for a person to approve. Here the question is specific: what happens to coat stock if the next three weeks move from ten units each to fifteen, twenty and twenty-five?
The accompanying conversation explains that forecast demand rises from thirty to sixty units, while the fifty units held and twenty due leave ten at the end. It presents the seasonal assumption for planner confirmation and advises checking the receipt and sizes before considering another buy. It does not present a conversation as a committed planning change.
Confirm the assumption, then track the result
MFP/WSSI provides View and Commit controls. Check the selected scope and the forecast basis before using the supported Commit workflow. The animation stops at a proposal awaiting confirmation; it does not change an operational plan.
As the season unfolds, compare actual sales with fifteen, twenty and twenty-five, and check whether all sizes stayed available. If sales fall short while medium is absent again, the cause may still be supply. If the coat is fully available and sells slowly, challenge the demand assumption rather than keep buying against it.
BEFORE COPYING LAST YEAR’S SALES
- Was the product available during the period being compared?
- Do the seasonal calendar and selling conditions still match?
- What is available now, and which receipts are still due?
- Is recent demand changing beyond a temporary uplift?
- Which forecast assumption needs confirmation before the next commitment?
A CLEARER NEXT STEP
Common questions
Can lost demand be calculated from ten weekly sales alone?
No. Those sales show what was sold while the size range was constrained. The fifteen, twenty and twenty-five forecast figures are explicit planning assumptions, not a calculation of missed customer demand.
What is MFP/WSSI in Merchmix?
MFP/WSSI is Core’s merchandise planning workspace. It brings weekly sales, stock, intake and financial assumptions together so the planner can assess what a demand change means for the stock plan.
Does a higher forecast always require another purchase order?
No. In this example, fifty units held and twenty already due cover sixty forecast sales and leave ten. Another twenty would leave thirty. The planner still needs to check required cover, size availability and receipt timing before deciding.
THE DECISION TRAIL / YUKTI
Keep the context.
Explain the response.
Yukti explains why the proposed sixty-unit forecast leaves ten units after the incoming order. The planner confirms the assumption before progressing a supported change.
- 01Identify constrained history
Ten weekly sales were recorded while medium was unavailable.
- 02Account for supply
Include fifty units held and twenty due in week two.
- 03Confirm the outlook
Approve the assumption, then compare actual sales with the weekly forecast.
FROM SALES HISTORY TO A STOCK DECISION
A forecast in context.
A clearer stock decision.
Use Core’s MFP/WSSI to connect the demand assumption with availability, weekly stock and incoming supply. In this example, sixty forecast sales and seventy available units leave ten, so a stronger outlook does not automatically mean another order.