What’s the Impact of Your Promotions?

It’s the little details that are vital. Little things make big things happen. – John Wooden

As a retailer, how important are promotions to your business?

Whenever we engage with a new retail client, this is one of the first questions we ask. Promotions – particularly short term price promotions – can have a profound impact on the supply chain (think about trying to shove a basketball through a garden hose) and pretty much always requires some significant thought around processes to plan and execute them properly.

More often than not, we’ll get an answer along the lines of “We do 30% of our business on promotion.”

How do they come up with this number?

Virtually all modern point-of-sale systems will flag a sale as promotional when it is being transacted, which makes things pretty simple: Sum up all of your sales where a promotional code has been affixed by the POS system, divide it by your total sales for the same time period and voila – you get a percentage you can recite to anyone who asks.

But does that actually mean “you do 30% of your business on promotion” or does it just mean that 30% of the sales you transact have a promotion identifier applied by the POS system?

If the overall goal of promotions is to drive additional sales and traffic, you can’t really measure them against that goal unless you know (or can reasonably estimate) a number of things, beyond just the sales that were recorded: 

How many customers were going to buy promotional items at full price that week anyhow?

  • How many customers were going to buy promotional items at full price in future weeks but purchased decided to purchase earlier and/or in larger quantities to take advantage of the promotional price?
  • How many customers were going to buy a different brand at full price, but switched to the brand that was on sale?
  • How many customers were going to pay full price for a different brand, but switched to a promotional item instead?
  • How many sales did you miss because a number of stores ran out of stock before the promotion ended?
  • Etc.

The specific impact of each of these consumer behaviours can vary item by item and store by store. Even worse, none of this information is stored in your POS system (or anywhere else), so if that’s all you have to work with, it’s really tough to understand the true impact of promotions on your business.

But what if you had a process and a system at item/store level that could:

  • Identify promotions and other events in your sales history; and
  • Estimate and isolate the incremental impact of those events for the purpose of developing a baseline forecast?

This would give you a view – for every item at every store – of what your sales would have been in each week that was impacted by a promotion:

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The methods for calculating “sales that would have been” will differ, but this type of sales history cleansing/segmentation is standard functionality for virtually all forecasting systems. Putting aside the “how”, the “what” gives you what you need to better estimate promotional impact:

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AI-generated content may be incorrect.

So now in addition to knowing that you sold 31 units at the promotional price, you also know:

  • The actual uplift in sales during the promotion week was 22 units – in other words, had the promotion not happened, you would have still sold 9 units at regular price that week.
  • This store ran out of stock 5 days into the promotion. Had that not happened the actual sales could have been 40 units.
  • Because of customer hoarding behaviour (or perhaps the stockout mentioned above persisted into the next week or two), your regular price sales for the next few weeks after the promotion declined by 11 additional units.
  • When a competing item was on promotion a few weeks later, this item was cannibalized to the tune of about 15 units.

This is the story for one particular item at one particular store and in sales units only – and that’s the whole point. When you plan in this way at the most granular level, you can gain insights at every level above it that can help you with planning future promotions, by understanding:

  • What was our true incremental sales gain from promotions?
  • Was our incremental sales gain constrained due to out-of-stocks during promotional periods? How do we factor this into our forecasts and stocking plans for future promotions?
  • How much did we sacrifice in regular price sales and what was the true incremental profit gain from our promotional activity?
  • Does the incremental profit gain reasonably offset the additional costs of promoting items (advertising, signage, store labour, logistics costs, etc.)?

Knowing that promotions are key to your business is one thing. But knowing their true impacts and tradeoffs to sales and profitability can really help you make better decisions that will squeeze maximum value from your promotional activity.

Shaping the Plan to Your Will

I am a man of fixed and unbending principles, the first of which is to be flexible at all times. – Everett Mckinley Dirkson

As a retailer, if you can accurately forecast the impact of your promotions – down to item/store level – within a narrow range, then everything will be fine.

Umm, okay, that sounds great but what if – hypothetically speaking – you’re not always able to do that? Then what?

Flowcasting has been fairly accurately described as a demand driven supply chain planning approach, with “demand” in this context referring solely to pure demand from consumers at the shelf.

In order for Flowcasting to work properly, the forecast of future demand at each item/store must be representative of what you expect to sell in every planned week in the future. While the starting point for the forecast can be derived mathematically by detecting patterns in history, it needs to be augmented when you know something about future consumer demand that will be different from the past (sometimes referred to as “demand shaping”). In this case, you know that you’re going to advertise a price drop to your customers in Week 9:


In the example above for an item at a store, we expect to sell 64 units on the promotion. This store needs to maintain 20 units of minimum stock at all times to keep the shelf display looking presentable. Flowcasting logic ensures that the Projected On Hand will never fall below that Minimum Stock in any future week, so as a result, the high expected promotional demand in Week 9 triggers 66 units to arrive at the beginning of that week (all requirements rounded up to shippable packs of 6 units). With a 1 week lead time, that 66 units is seen by the servicing DC as a shipment that will be made to that store in Week 8.

We’re only looking at a single store here and there are a variety of ways to have the promo uplift applied (top-down based on proportional contribution to past total sales,  promo sales or baseline forecast, elasticity curves, machine learning based approaches, etc.). The key point here is that demand must be appropriately shaped and represent what you actually expect to sell.

What we have here is a really good plan… If you’re confident in your promotional forecast and if you’re just going to put a promo tag on the home location. For a lot of products (e.g. those that you’ve promoted frequently at the same price with no additional merchandising support), this might be just fine and dandy.

But what if you need product to be in the store earlier or in greater quantities than required just to support expected sales? This could be to support the set up of off-shelf displays or cover for upside forecast risk (particularly if shipments to the store are relatively infrequent and there may not be enough time to do a “mid-course correction” once the promotion starts).

This need is sometimes referred to as “push/pull” or “decoupling” and it can be a real challenge, especially when your supply chain is… well… decoupled.

Flowcasting is uniquely capable of solving this problem quickly, precisely and well in advance so that everyone (store operations personnel, support office planners, buyers and suppliers) can see what’s going to happen.

Because Flowcasting connects the entire supply chain from the consumer to the supplier – it doesn’t support “decoupling” – it completely invalidates it.

For example, suppose that the item we planned earlier will be supported by an off-location display of 30 units in addition to the 20 units required as a minimum on the shelf. Furthermore, the stores need to have sufficient stock a week ahead of time to organize their merchandising teams to set up the display.

In Flowcasting, this is executed as a simple, future dated temporary change to the minimum stock:

Instead of stock arriving just in time to support sales, a large shipment to support the additional display will arrive the prior week, while the additional stock to support the sales uplift will arrive later.

Okay, but what if you’ve never promoted this item at this price point before? The forecast is your best unbiased guess at what’s going to happen, but you would rather have additional stock at the store than risk running out.


Here, we’ve set our minimum stock during the promotion week to ensure that we’re covered if we sell double what we expect.

What if this store can get multiple shipments during the promotional week? You can instead apply a safety stock uplift to the distribution centre plan so that the stock is positioned there to quickly refill stores that are selling through it more quickly, while not overloading the stores that aren’t.

Or you can split the difference by adding some of the additional safety stock to the stores and some to the DCs. Or… you get the idea. All nodes are planned and all nodes are connected, so the effect of changing the shape of the supply plan is precise and the impact on all nodes is transparent.

And by planning in this fashion (shaping the supply plan separately and independently from shaping the demand), there is an additional advantage over pushing stock out via allocation: continuous replanning. The planned shipments and arrivals will be recalculated every day as sales and inventory movements are realized between now and when the promotion starts. And everybody sees how the plan is shifting over time at every location, right back to the supplier.

While there are other methods for shaping the flow plan (temporarily bypassing nodes with planned network flow changes, days of supply/safety time, etc.), simply having separate levers for demand shaping and supply plan shaping is a very effective way to plan not just promotions, but any other scenario where “decoupling and pushing” would be used outside of a Flowcasting context:

  • Cannibalization and halo effects on items that compete with or complement a promoted item
  • Planning for the initial pipeline and shelf filling, followed by ongoing replenishment for a new item
  • Pre-building stock ahead of a seasonal or holiday peak

Plan the execution, then execute the plan.

What could be simpler?