Cybex Retail AI
AI Insights · Case Study

Why growth slowed in week 27.

A retail chain’s sales growth halved in a single week, from +17.4% to +7.3%, and its plan beat narrowed to the thinnest margin in seven weeks. This is what the data said, how long it took to find, and what it is worth to fix. All figures measured against the live database; the client is anonymised throughout.

The answer, in four lines.
  • More customers came in, and fewer of them bought. Footfall rose 4.0% in week 27 and 26.6% across the six weeks, while conversion fell from 18.5% to 17.5%. Demand was not the problem.
  • Most of the slowdown was not a slowdown. Last year's week 27 was 6.7% bigger than its week 26, so the comparison hardened on its own.
  • The real decline was availability — and it cost transactions, not basket size. Basket composition was tested against availability at department and store level and shows no relationship. Fewer customers found what they came for, worth about $101,000 in week 27 alone across the sixteen measured stores.
  • The cause sits upstream. The business has bought 0.74 units for every unit sold this year. Warehouses absorbed the gap until they could not.

1. The week in question

Growth vs last year
+7.3%
Previous week
+17.4%
Vs plan
+2.2%
Transactions
−1.8%
Average ticket
−0.7%
+0% +5% +10% +15% +20% +25% 17 13 21 14 15 15 13 16 27 17 12 18 8 19 4 20 9 21 10 22 13 23 16 24 15 25 17 26 7 27 Retail week
Sales vs last year, %. Fifteen consecutive weeks of growth, then week 27 — highlighted — halves to +7.3%, still ahead of plan.

The headline drop is 10.1 points. Splitting it matters, because nearly three quarters of it is arithmetic rather than performance:

ComponentPointsWhat it is
Harder prior-year base7.3Would have happened with sales flat week on week
Actual sales decline2.8The part that is genuinely this year
The decline is mostly transaction count. Basket size barely moved. Whatever happened, happened before the till — which leaves two candidates: fewer people came in, or fewer of the people who came in found what they wanted. Section 2 settles which.

2. More customers came in. Fewer of them bought.

Sixteen stores report door count across the whole six-week window. Their traffic, transactions and conversion, week by week:

Retail weekTrafficTransactionsConversionSales
22169,80130,35917.88%1,365,896
23171,32731,62618.46%1,470,925
24182,02133,98818.67%1,590,175
25199,71736,99518.52%1,726,489
26206,75338,18518.47%1,793,796
27214,99437,53917.46%1,744,690
Traffic rose every single week — including week 27. Footfall grew 26.6% across the window and was up a further 4.0% in the week growth stalled. Conversion held between 17.9% and 18.7% for five weeks, then fell to 17.46%. Transactions dropped while more people were walking through the door.

That is not a demand problem. The customers arrived; the sale did not happen.

2.1 What the conversion drop cost, in one week

Conversion, weeks 22–26
18.4%
Conversion, week 27
17.5%
Transactions lost
2,168
Sales forgone
$101,000

Had week 27 converted at week 26's rate, its 214,994 visitors would have produced 39,707 transactions rather than 37,539. At the week's own average ticket of $46.48 that is roughly $101,000 of sales, in one week, across sixteen stores — before counting the nine sites without door counters.

On the year-on-year traffic figures. They are deliberately excluded from this analysis. Door-counter coverage expanded during the year, so the store set behind this year's traffic is not the store set behind last year's, and the comparison overstates growth. The six-week view above is a fixed panel of the same sixteen stores throughout, so it is unaffected — and it is the view that answers the question.

2.2 And the baskets themselves held

If shoppers were being turned away by empty shelves, the baskets that did get rung should show it — thinner, fewer add-ons, more single-item sales. Across 214,818 transactions in the window, they barely moved.

Basket measureWeeks 22–26Week 27Change
Baskets analysed176,12938,689
Single-style baskets40.0%40.7%+0.7 pts
Two styles or more60.0%59.3%−0.7 pts
Three styles or more35.3%34.2%−1.1 pts
Styles per basket2.462.42−0.04
Units per basket2.782.62−0.16

There is a compositional shift underneath — the share of baskets containing each department moved more than the totals suggest:

DepartmentIn weeks 22–26In week 27ChangeIn-stock change
Department 165.9%65.3%−0.6 pts−4.0 pts
Department 547.9%45.3%−2.6 pts−1.7 pts
Department 437.4%41.7%+4.3 pts−2.8 pts
The shift does not follow availability — and that is the point. Department 1 lost the most availability by a wide margin, four full points, and its basket penetration moved 0.6. Department 4 gained 4.3 points of penetration while losing 2.8 points of stock. Whatever is moving the mix, it is not the stockouts.

The same test at store level returns the same answer. Across the ten largest stores, in-stock fell between 3.0 and 6.7 points, while units per basket moved between +0.26 and −0.16 — noise, with no relationship to the availability change. One store lost 6.7 points of in-stock and its basket was flat; another lost 4.9 points and its basket grew.

-0.2 -0.1 +0.0 +0.1 +0.2 +0.3 -7 -6 -5 -4 -3 In-stock change, week 27 vs prior five weeks (points) Units per basket, change no basket change
Availability against basket size, ten largest stores. Every store lost between 3.0 and 6.7 points of in-stock, yet basket size moved independently of it — the points form no slope. If stockouts were thinning baskets, they would fall left to right.
What this rules out, and why it matters. Availability did not shrink the basket. It cost transactions — visits that did not convert at all. That narrows the diagnosis considerably: the fix is getting the right stock in front of the customer who is already in the store, not merchandising the add-on. A basket-building programme would have addressed the wrong thing.

3. The root cause: the buy has not kept pace with the sell

Units received (1 Feb – 8 Aug)
883,741
Units sold, same period
1,195,325
Replacement ratio
0.74
Warehouse stock, 6 weeks
−19%

For every four units sold this year, three have been bought. The difference came out of inventory. The warehouses absorbed it for most of the year — which is precisely why nothing appeared in the sales line until the buffer thinned.

Retail weekWarehouse stockStore stockStore coverIn-stock
22992,580579,7410.9983.1%
23985,279586,6401.1382.6%
24931,134582,5780.9081.8%
25890,108575,7201.0080.6%
26839,485563,3410.8679.1%
27804,313537,8720.7377.6%

Store cover is units flowing into stores divided by units sold. Above 1.0 the network builds stock; below it, drains. The warehouses drained nearly three times faster than the stores — −19% against −7% — which is the signature of a distribution network working correctly against an inbound supply that is too small. The goods were not stuck in the warehouse. They were never bought.

0.25 0.50 0.75 1.25 1.00 replenishing draining 0.99 22 1.13 23 0.90 24 1.00 25 0.86 26 0.73 27 Retail week
Units received per unit sold, by week. Warehouses excluded. Below 1.00 the stores are selling faster than they are being refilled — four of the six weeks, and 0.73 by week 27.

4. Where it bites: the A stores

The seven highest-selling stores carry the trade, and every one of them was short-fed over the six weeks to 8 August.

StoreUnits soldStock, startStock, endChangeWeeks coverReceived per unit soldIn-stock
Store A175,20677,27266,919−13.4%5.30.8780.5%
Store A261,65932,65525,304−22.5%2.50.8983.4%
Store A361,41269,21057,206−17.3%5.60.8384.6%
Store A444,51517,75817,256−2.8%2.30.9886.9%
Store A541,24229,24723,946−18.1%3.50.8787.8%
Store A639,82938,18634,082−10.7%5.10.9285.7%
Store A735,32341,50331,773−23.4%5.40.7483.4%
Every A store received less than it sold. The ratio runs 0.74 to 0.98 — not one reached 1.0. Stock fell at every one of them, by as much as 23%. The two thinnest are A2 at 2.5 weeks' cover and A4 at 2.3 — the busiest stores in the chain running the leanest.

Meanwhile a mid-volume store sits on 11.6 weeks' cover and 37 units per square foot, roughly double the chain norm. The surplus is not where the trade is.

4.1 And the stock the A stores hold is the wrong stock

Units in broken size runs, two largest stores
25,429
Of missing sizes, sourceable anywhere
24%
Of missing colours, sourceable
47%
A-store styles fully presented
31–38%

At the busiest stores, 19–22% of units sit in styles with a broken size run, and only about a third of styles are complete on both size and colour. Four in five of the missing sizes do not exist anywhere in the network — which is the replacement ratio showing up on the shop floor. Runs break as they sell through, and there is nothing behind them to repair with.

Fully presented styles are in stock 93.2% of days against 86.1% for incomplete ones, and that holds at every one of the seventeen trading stores. Presentation is an availability lever, measurably.

5. What we had to build to answer the question

The warehouse held no history of stock on hand. The inventory table is a live snapshot with no date, and the history table is empty. On day one, "what was in stock six weeks ago" was unanswerable — for any store, any week.

We rebuilt it. Anchoring on the current snapshot and walking the movement ledger backwards produced a daily stock position for every SKU at every site: 3.8 million rows across 43 days, with the anchor day reconciling exactly to the live snapshot and zero day-over-day discontinuities. Every in-stock and cover figure in this document comes from it.

The ledger also revealed a process gap. The reconstruction goes negative on 2,570 SKU-and-store lines — 10,000 units across all 24 sites. Negative stock is impossible, so these are units moved without a transfer being recorded. It matters beyond tidiness: replenishment reads the same on-hand figure, so a line showing stock the floor does not have looks covered and is never reordered.

6. What it is worth

From the companion distribution analysis, measured on the same database:

ActionUnitsRetail valueComment
Ship what the warehouses already hold93,177$1,686,206Bought, paid for, sitting still
Rebalance surplus between stores8,718$138,336Matched shortage against genuine surplus
Consolidate dead broken runs out of A stores16,571720 styles; frees prime selling space
Service level today
47.3%
Achievable without buying
68.4%
Recoverable now
$1.82M
Overstock beyond 12 weeks
$1.54M

A 21-point improvement in service level using stock the business already owns. No purchase order, no additional working capital.

7. Proposed engagement

Four workstreams. Each stands alone and delivers on its own; none waits on the one after it.

#WorkstreamWhat it deliversWhy now
1 Full insights analysis The complete diagnostic across trading, availability, assortment and supply — with the stock-history layer made permanent so the questions stay answerable. Today the history has to be reconstructed each time. A nightly snapshot makes every future question a query rather than a project.
2 Immediate DC distribution and re-allocation Ship the $1.69M the warehouses already hold; rebalance $138k between stores; pull 16,571 units of dead broken runs out of A-store space. Fastest return in the programme and it needs no forecast. Same pick lists, same warehouse process — only the quantities and the order change.
3 Forecast-based purchasing Replace the static minimum with a demand-derived target as the buying driver, keeping pack rounding and presentation floors intact. The 0.74 replacement ratio is the root cause. Distribution moves what exists; only buying changes how much exists.
4 Weekly assortment planning Size and colour completeness by store and grade, reviewed weekly, with the replenish-versus-clear decision made on velocity rather than on age. Runs break continuously at the A stores. A weekly cadence catches them while they are still repairable.
Sequencing. Workstream 2 pays for the programme and can begin immediately — it requires no new model and no change to warehouse operations. Workstream 3 is where the structural fix sits. Workstream 4 keeps the gain from decaying, and workstream 1 makes all three measurable.

8. Basis, and what this analysis does not claim

Anonymised. Store names and locations are replaced with rank labels — A1 is the highest-selling store, A7 the seventh. Every figure is unchanged.
  • Full dataset, no sampling. Every figure is measured against a full copy of the live trading data. Trading, availability and movement figures cover retail weeks 22–27, complete to the end of week 27.
  • Availability is measured, causation is inferred. The chain of evidence — receipts below sales, warehouses draining, in-stock falling, traffic rising while conversion falls — is consistent and each link is measured. It is not a controlled experiment, and the per-store correlation between availability and sales is not strong enough to attribute a precise revenue figure to any single store.
  • Traffic is measured within the six-week window only, on a fixed panel of the sixteen stores reporting door count throughout. Year-on-year traffic comparison is excluded because counter coverage changed during the year. The $101,000 figure covers those sixteen stores for one week and is not annualised.
  • Unmet demand is not lost revenue. Customers substitute, defer and return. The recoverable figures above are gross exposure; a measured substitution rate is a workstream 1 deliverable rather than an assumption baked in here.
  • Full size and colour runs improve availability, not obviously sell-through. Across all seventeen stores, complete styles are in stock materially more often but do not demonstrably sell through faster. The presentation rule is recommended on the availability evidence, and the sell-through question is left for a controlled pilot.
Cybex Retail AI · AI Insights case study · prepared August 2026.
Measured against a full copy of the live trading data — complete dataset, no sampling. Trading, traffic and availability figures cover retail weeks 22–27 and derive from a reconstructed daily stock history built for this analysis. Traffic is a fixed panel of the sixteen stores reporting door count across the whole window. Store names and locations are anonymised; all figures are unchanged.

Questions like this hiding in your data?

Tell us the decision you want AI to improve first — allocation, replenishment, forecasting, pricing — and we will show you what a 6–8 week pilot on your own data looks like.

Request a Briefing