
A BWS Jacobs Creek draw advertises a $50,000 prize and runs to 1 January 2027 — months after the sales it drives will have been reported.
That gap is the whole problem with promotional ROI. The honest number on a promotion isn’t the lift you see during the campaign; it’s the lift minus the slippage you forecast and minus the demand you pulled forward. Which means a promotion’s return can only be settled a quarter after it closes, not on the day the entries stop. Read it off the entry report and you’ll book a win on volume you already owned.
This is the operator’s view: not how to build a dashboard, but what the number actually contains and when it’s safe to sign.
How do you measure promotional ROI?
Promotional ROI is net incremental revenue over total cost — where incremental means above the baseline you’d have had anyway, and cost includes the reward net of forecast slippage. Because a promotion can pull demand forward, the number isn’t final until you’ve seen the quarter after it closes.
Why the in-window lift isn’t the return
Take a purchase-to-enter promotion on a pantry staple. Sales lift in the campaign window, the report goes out the week the entries stop, and the in-window number quietly contains two things it shouldn’t: the volume you’d have sold anyway, and the volume a shopper brought forward by stocking up now instead of next month. A CFO can dispute the first — that’s what a baseline is for. The second one the entry report can’t see at all.
The buyer who filled the trolley in October to grab a draw entry wasn’t going to buy again in November regardless. A window-only ROI figure counts that October volume as a gain and then loses it next quarter, on someone else’s number. The lift is real; the return is not the same thing.
So the in-window lift is a gross figure. The return is what’s left once you subtract the sales you would have had anyway and the sales you simply moved forward. That subtraction is the work, and it can’t happen until the forward-pulled demand has had its chance to not show up.
The cost line most reports get wrong
The denominator is where cashback and claim-based mechanics quietly mislead. The advertised reward value is not the cost. On a claim-based promotion, the people who never claim are budget that stays in the account — so the true cost in the ROI denominator is reward value net of forecast slippage, not the headline the pack carries.
Say the plan advertises a cashback and budgets the full reward pool as cost. If a known share of eligible buyers never complete the claim, that unredeemed value never leaves. Charging the full advertised pool into the denominator overstates your cost and understates your return — the opposite error to the one in the revenue line, and just as wrong. You want both honest, not one padded to cancel the other.
This is why slippage isn’t a rounding detail. It’s a forecast you make before launch and reconcile after, and it moves the ROI number in a direction the entry report can’t see. Add in the costs that briefs routinely leave out — permits, fulfilment, the internal hours — and the fully loaded denominator rarely matches the one in the first-week deck.
Why a quarter, not a week
Look at what’s actually live. Promo Monitor tracks the Australian market, and prize draws are the dominant mechanic right now — these are mechanics whose return is settled on redemption and post-period behaviour, not on entry count. The entry is an action, not an outcome.
And the entry window often doesn’t line up with the sales window at all. That BWS Jacobs Creek draw, advertised at a $50,000 major prize, runs from 9 September 2026 to 1 January 2027. The sales effect clusters where the product moves; the draw tail runs for months after. There’s no neat reporting date where the entry report and the sales effect both resolve on the same day — so a figure dated to campaign close is measuring an event that hasn’t finished happening.
A quarter is the right settlement window because that’s roughly how long a pantry-load burns down and how long it takes for the next cycle of retail scan data to come back and show whether the category dipped below baseline once the offer stopped. Only then do you know whether new buyers came back, whether basket sizes held, and whether you created demand or borrowed it. Watching a campaign against forecast as it runs — the kind of live view a single reconciled data source makes possible — tells you where the number is heading, but the settlement still waits for the quarter.
The counter-position: get incrementality right and report now
A fair objection: measure net incremental revenue over total cost against a baseline for the campaign window, get the incrementality right with a holdout or a matched cohort, and the number is defensible. Waiting a quarter just delays the report the CFO already wants.
Half right. A proper baseline does fix the first error — it separates lift from the growth you’d have had anyway. What it can’t do inside the window is see demand you pulled forward. Picture two identical cells: same baseline, same in-window lift. In the first, buyers draw down what they stockpiled and the next quarter sits on baseline — the lift was genuinely new demand. In the second, the next quarter dips below baseline as the stockpile burns off. Measured to campaign close, both report the same ROI. Settled a quarter later, the first holds and the second shrinks, because the forward-pulled volume was never incremental — the same spend now sits on top of fewer net new sales, so cost per incremental customer rises. The entry report cannot tell these two apart.
A matched-market or split test doesn’t save you here if the control cell lives under the same seasonal and promotional calendar, because it stockpiles too — both cells pantry-load ahead of the same period, so the difference between them flatters the test cell and hides the forward-pull they share. That effect is largest exactly where it costs most: storable categories and high-value cashback mechanics, where a shopper will happily buy six months of product to clear a claim threshold. The baseline answers “versus no promotion.” It doesn’t answer “versus next quarter.” You need both, and the second one takes time to arrive.
So report a provisional number at close by all means — just label it provisional, and settle it when the forward-pull window has passed. That’s not delay for its own sake. It’s the difference between a figure that survives scrutiny and one that gets quietly revised when the same “winning” mechanic is run again and the real cost per incremental customer finally surfaces. Bamboo’s piece on how to measure shopper marketing ROI takes the demand-side view of the same split.
A promotion’s ROI isn’t a number you read off the entry report; it’s a number you settle a quarter later, once you know what you created and what you merely borrowed.
If you’re rethinking how you measure promotional ROI, we’d be happy to talk it through.
