- Lisa Maas
- 5 hours ago
- 4 min read
It’s an important question with often-murky answers: Did a promotion actually move the needle for the business? Although today’s brands and retailers have many tools at their disposal to launch promotions, it is challenging to discern the impact of such efforts. Many promotion analyses can’t distinguish between selling more items and notably improving performance.
When you get down to it, a promotion drives real growth only if it sells more than the company would have sold anyway. This truth matters in an ever-competitive omnichannel marketplace.
For example, a BOGO offer on a newer product may lead to sales gains across a retailer’s footprint. The marketing team sends the results to finance, the program gets renewed, and everyone moves on. But four weeks later, the category is flat (and sometimes even lower) and explanations are vague. So, did the promotion just shift when consumers bought the product?
Focus On the Right Number
Most promotion reports compare promotion week to the week before it, or to the same week in the prior year. But a before-and-after comparison doesn’t reveal the invisible figure where the truth hides – what would have happened in any case. When a promotion pulls demand into a tight window, it basically manufactures a peak. If sales drop below baseline once the discount ends, the promotion borrowed from next month rather than genuinely creating growth.
That borrowed volume is referred to as “pull-forward”: sales from customers who were going to buy regardless, just sooner. Pull-forward is not new money. It is the same money, moved earlier in time, usually at a thinner margin. A promotion that posts a 12% bump during the promotion window can net zero incremental annual sales once the post-period slump is counted, and a report that stops at the spike won’t show it.
How much a promotion borrows depends heavily on what is being sold. For instance, if a beverage is promoted and shoppers tend to drink the extra product, real consumption goes up. On the other hand, if laundry detergent is promoted and the consumer simply stocks their shelf at home, they tend to wait a bit to make another purchase. In these two cases, the discount is similar, but the economics are opposite. A measurement approach that ignores category behavior will misread both.
What a Standard Promotion Report Misses
Standard reports can be inaccurate because the effects of price and distribution are not controlled for. Attribution, then, may be misdirected.
Cannibalization within the portfolio. A deal on one pack size can drain volume from the brand's own non-promoted SKUs, so promoted-item lift overstates what the brand actually gained.
Halo into adjacent categories. Sometimes a promotion lifts complementary products alongside it. Promoted-item reporting misses this key metric.
The post-period baseline drop. The clearest fingerprint of pull-forward, and the part single-window reporting is structurally blind to.
Instead of working from assumptions, brands can use results that start with store-level POS data to help answer the pivotal question of promotional impact on business growth.
Three Ways a Promotion Report Tells You It Worked When It Didn't
Overstated promotion claims trace back to certain habits. Most fundamentally, failing to control for other factors can lead to misleading conclusions. To accurately assess promotional effectiveness, analyses must account for key drivers such as distribution and price, isolating the true impact of the promotion from other influences on performance. Other potentially-problematic habits include:
Stopping the clock too early. Comparing the promotion week to the week before ignores seasonality and doesn’t capture the post-period dip where pull-forward shows its hand.
Reading the promoted item instead of the portfolio. Promoted-SKU lift is the easy number. Category and portfolio lift after cannibalization is the honest one.
Treating repetition as evidence. Running the same promotion every year and pointing to each in-window spike isn't proof it works. The only proof is whether the brand would have hit its annual number without it.
How to Measure Incremental Promotion Lift Without Holding Back Sales
There used to be tradeoffs in attempting to pinpoint real growth. While a dark market is a popular way to prove incrementality with marketers withholding the promotion from a set of stores and using them as a control, it can limit the overall sales potential and importantly, it’s no longer the only option to get a clear read on impact.
Modern tools now remove that tradeoff. Circana’s Liquid Testing solution is based on store-item-day point-of-sale (POS) data from more than 750,000 stores. It provides much-needed clarity: a promotion runs everywhere it was always going to run, and a control is built, not held back. The control is assembled from comparable stores using historical sales patterns, demographics, and category dynamics to model what the promoted stores would have done untouched.
Control methods work well because they provide forecast dependence. In contrast, no-control methods rely heavily on forecasting that assumes future trends mirror past patterns.
That said, there may be times when no-control methodologies are in order. Cost and logistical constraints may be a factor. A brand may also opt for a no-control approach for promotions with a short campaign window, like a product associated with a theatrical movie premiere.
What an Always-On Approach to Promotion Measurement Unlocks
Instead of a single retrospective study that doesn’t reveal the full picture, a standing always-on measurement practice changes how the calendar gets built. A brand that tests consistently across its major promotions through Circana’s Liquid Testing accumulates a working map of its own promotion economics, learning which promotion types grow the category, which impact timing/pull-through only, and which erode margin and should be eliminated. Liquid Testing is a flexible solution that can also address no-control use cases.
Ultimately, in an operating environment in which true growth can be hard to attain, the cost of getting it wrong is high. Circana’s Liquid Testing was developed to quickly identify– and ultimately help achieve – growth across every promotion.
