Why is "Treating the Event Margin as the only decision metric" a common mistake when using the Source-of-Volume Decomposer?

Symptom: Take the Step 5 case: switching at 80%, an Event Margin of $8,600, exactly what the GOLDEN event earns, and a Durable Value of only $3,096. The plan is approved on the event cash alone, and in the next planning cycle the category manager at the retailer pushes back hard: "our category did not grow." Fix: The Event Margin is the manufacturer-side cash. The Durable Value tells you how much of that cash is still there once the promotion ends, and the SoV quality band in the downloadable PDF (GOLDEN, PRODUCTIVE or MIXED) tells you how the event will land with the retailer. Always use both. A PRODUCTIVE event with a strong Event Margin still puts cash in your pocket. But when the Durable Value comes in low, most of that cash goes again, and there is nothing in the result you would want to show a buyer. Events that keep the retailer relationship strong over the long term need the GOLDEN verdict: Category Expansion at 25% or more of total uplift. You get there by pairing the mechanic with communication, such as a display, sampling and a genuine category claim, rather than a price cut alone.

Why is "Confusing the uplift with the net incremental volume left after the post-promo dip" a common mistake when using the Source-of-Volume Decomposer?

Symptom: A trade plan claims +10,000 incremental units and gets approved. Look again in Q+1, the quarter after the event, and the baseline had dropped by 3,500 units over the 3 weeks that followed, so the real net gain was ~6,500 units. Fix: Pantry loading creates a post-promo dip roughly equal to the pantry-loaded volume (3,500 units in our default = 3,500 unit dip spread over 1-4 weeks). The Unproductive volume tile on the main card is your early warning: whatever it reads is roughly the size of the dip you are about to book. Always report net incremental volume (uplift minus cannibalization, store switching and the dips before and after), not the uplift. The Promo Baseline Estimator (Tool #10) measures that baseline shift for you directly.

Why is "Over-indexing on Brand Switching as 'productive'" a common mistake when using the Source-of-Volume Decomposer?

Symptom: Brand Switching comes out as the largest source, and the team writes the event up as a win. Then in Q+2, two quarters on, the competitor comes back with a counter-promotion of its own, the same shoppers switch straight back, and the share you gained is gone. Fix: Switching is productive ONLY if the switched shopper stays. Whether they stay comes down to two things. First, whether anything gave them a reason to stay, such as the product genuinely being better, or the discount having bought a first trial of something new to them. Second, whether the competitor answers with a counter-promotion within 4-8 weeks. When switching is the dominant source, also check how many of the shoppers who bought during the event came back to buy again, and group them by when they first bought your brand. Switching that does not turn into a second purchase is a share gain that lasts as long as the discount did.

Why is "Ignoring the Consumption Increase share because 'it's the residual'" a common mistake when using the Source-of-Volume Decomposer?

Symptom: Trade plan commentary treats Consumption as 'whatever is left' and doesn't design for it. Result: Consumption Increase stays down at 0-15% of the uplift, and the chance to leave households using more of the product than they did before goes unused. Fix: Consumption Increase only counts as lasting net incremental volume if whatever made people use more carries on after the promotion ends. Designing for it means picking a mechanic that builds a habit: subscribe-and-save, multi-packs that reward using more, or a claim on the pack that puts the product into a specific moment ('great for lunchboxes'). Most trade plans in fast-moving consumer goods (FMCG) put very little money behind this one. Events built deliberately around Consumption Increase tend to do better over a full 12 months, even when the Event Margin they post during the event itself is lower than a pure-switching event would have delivered.

Why is "Using the 50-cent scenario math to make decisions about a 20%-off event" a common mistake when using the Source-of-Volume Decomposer?

Symptom: Someone plans a 20%-off event on the source mix the tool shows for its 50-cent default (about 10% off), and the verdict that looked PRODUCTIVE turns out to be MIXED once the real mix comes in, because the deeper cut loaded more into shoppers' pantries. Fix: The two thresholds hold up reasonably well whatever the discount depth: 70% or higher on the Net Share of Uplift, 25% or more on Category Expansion. The dollar figures underneath them do not hold up, because a different discount depth means a different promo margin on every unit. A deeper discount usually changes the mix in two ways. You get more pantry loading, because shoppers stockpile more at 20% off than they do at 10% off. And the bigger cut may pull in a few shoppers who were not buying the category at all, something 10% off rarely does. The tool fixes scenario inputs at 50 cents off / $0.86 promo margin. To read it for a different discount depth, work out the new promo margin yourself first (the $1.36 a full-price pack earns you, less what you fund on each pack sold on deal), then adjust what you expect the mix to look like. For a real multi-depth comparison, cross-reference the [Promo ROI Calculator](/tools/promo-roi-calculator) which lets depth vary.

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Source-of-Volume Decomposer

Split the extra volume a promotion delivered into its four standard sources (Switching, Expansion, Pantry, Consumption) and see which one is largest. Then read the Event Margin, the cash the event banks while it runs, against the Durable Value, the part still there once the promotion ends, before you sign the trade plan. The same interactive model the full RGM Academy course uses for TPO Lesson 2, no sign-in, no paywall.

Updated 13 October 2026Extracted from the Trade Promotion Optimization module, lesson 2: Source of Volume Decomposition

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Guided walkthrough

Explore the tool, from setup to common mistakes

Five short sections explain the scenario, what each control does, how to read the output, and the mistakes to avoid. Open whichever helps. The tool above works without them.

5.1Scenario setup

The starting SKU, market, and assumptions the model makes.

You are the Trade Marketing Director on a mainstream biscuit brand. Your Q4 trade plan has a feature‑and‑display event on the 250g SKU at 50 cents off, $4.99 to $4.49 on the shelf. Sales delivered: the event ran for one week and sold 15K units against a 5K baseline for that week, so the uplift, promoted volume minus baseline, was 10K units. The volumes are the tool's own illustration: a 10 percent cut on feature and display rarely triples a week's sales on its own, so read the shape of the split rather than the size of the uplift. The Sales team wants to run the event again in Q1. Finance has asked for the source‑of‑volume decomposition before signing off. They want to know whether the 10K uplift was genuine growth or whether it was mostly your own loyal buyers stocking up.

Your job by Friday is to split the 10K uplift into the four standard sources. Brand Switching is volume that came from shoppers leaving another brand. Category Expansion is people buying the category who otherwise would not have bought at all. Pantry Loading is your own loyal buyers stocking up early, which comes back as the dip after the promotion. Consumption Increase is households simply using more of the product. Then calculate the Net Share of Uplift (net incremental volume divided by the uplift: of the extra units, the share that was genuinely new), the Event Margin, and the Durable Value, and hand Finance the verdict the downloadable PDF gives the event: GOLDEN / PRODUCTIVE / MIXED / UNPRODUCTIVE. Finally, test whether a deeper discount (30%) or an even shallower one would tilt that mix in a better direction.

Your objective

Use the decomposer to read the current mix and find the source that contributed the most volume. Then put the event in one of the four verdict bands, and test one idea for improving the mix before you commit the Q1 trade plan.

Key assumptions

The four sources are mutually exclusive and sum to 100% of the uplift. Consumption Increase is whatever the other three leave of the 100%. It is NOT a separate slider. This matches the interactive model inside the lesson exactly. The three sliders you set are Brand Switching, Category Expansion and Pantry Loading, and between them they are meant to stay inside 100%. Push them past it and the tool warns you in red that the sources exceed 100%, and it holds Consumption Increase at 0 until you pull one slider back.
Net incremental volume = Switching + Expansion + Consumption. Net incremental volume is the part of the uplift that is genuinely new: uplift minus cannibalization, store switching and the dips before and after, plus any measured halo. This tool has no cannibalization or store switching slider, so Pantry, the dip after, is the only source treated as unproductive. That is how these four behave in the field. Brand Switching takes share off a competitor, which earns its place as long as those shoppers stay with you. Category Expansion brings in demand that was not in the category at all, and it is the source most likely to still be there next quarter. Consumption Increase is a change of habit, so it counts if the habit holds and falls back to the old baseline if it does not. Pantry is pure timing shift (bought now instead of next week, creating a post‑promo dip).
Two headline numbers. The Event Margin is the cash the event earns while it runs, before any adjustment for what happens afterwards. Every unit of net incremental volume earns the $0.86 promo margin, and then the 50‑cent pantry cost on each pantry‑loaded unit comes off. The Durable Value asks how much of each source of net incremental volume is still there once the promotion ends, and weights it accordingly: Category Expansion counts in full at 1.0, Consumption Increase at 0.8, Brand Switching at only 0.25. The same pantry cost then comes off. Durable Value always lands at or below Event Margin. The wider the two numbers sit apart, the more of your event cash disappears once the promotion stops. Pantry volume costs 50 cents a unit, the difference between the full margin ($1.36 on your $3.46 of Net Sales) and the promo margin ($0.86, after the 50 cents you fund). Those units were coming anyway, so the discount on them buys nothing. This split is the core economic claim the framework rests on.
The Source‑of‑Volume (SoV) Quality verdict, which the downloadable PDF gives the event, puts it in one of four bands, using rule‑of‑thumb cut‑offs on the Net Share of Uplift. GOLDEN needs two things at once: a Net Share of Uplift of 70% or higher, and Category Expansion supplying 25% or more of the total uplift. That is a shared gain, the event where the retailer's category grows at the same time as your share, which is the easiest kind of plan to get signed. PRODUCTIVE is the same 70% or higher, but with Category Expansion under 25% of the uplift. MIXED is 50% or more and anything below 70%. UNPRODUCTIVE is below 50%. That 25% expansion threshold is what separates an event that is good for you from one that is good for the retailer too.
The scenario fixtures are fixed in this sandbox (one 250g biscuit SKU, $4.99 to $4.49 on the shelf, $1.36 to $0.86 of the brand's margin). The shelf price and the deal price are the retailer's call. The brand's margin starts from its Net Sales: the retailer pays $3.74 a pack, everyday trade terms take that to $3.46, and $2.10 of cost leaves $1.36. The retailer keeps its usual cash margin on the deal, so the brand funds the whole 50 cents. In a real decomposition the SKU, the shelf price, how deep the discount goes and the margin structure all change from one case to the next. What this tool teaches is the shape of the calculation and the thresholds a verdict has to clear, rather than the exact dollars for your own category.

5.2Controls & toggles

Every input the calculator exposes, its range, and what it changes.

Control	Range	Default	What it changes
Total promotional uplift slider	2,000 to 25,000 units (500-unit step)	10,000 units (mid-range self-demo)	The uplift: every extra unit beyond baseline, before asking where it came from. Every dollar figure on the page moves in step with this slider. The Net Share of Uplift and the PDF's SoV quality verdict do not, because they depend only on each source's share of the uplift. So moving this slider changes both the Event Margin and the Durable Value proportionally without moving the quality verdict.
Brand switching %	0 to 80% (5% step)	30% (3,000 units at 10K uplift)	Counts as net incremental volume. Volume stolen from competitor brands, a brand gain. Switching counts toward the 70% Net Share of Uplift threshold, but it does nothing for the 25% Category Expansion threshold that GOLDEN also requires. An event built purely on switching therefore tops out at PRODUCTIVE in the downloadable PDF, however high the Net Share of Uplift reads.
Category expansion %	0 to 50% (5% step)	15% (1,500 units at 10K uplift)	Counts as net incremental volume AND is the GOLDEN‑trigger. Once Category Expansion supplies 25% or more of the total uplift, and the Net Share of Uplift is already at 70% or higher, the PDF's verdict turns GOLDEN. The single most valuable source. Retailers measure their own category growth on this line.
Pantry loading %	0 to 70% (5% step)	35% (3,500 units at 10K uplift, the dominant source in the opening mix)	Unproductive source. It costs you 50 cents a unit, the full margin less the promo margin. Creates the dip after the promotion. Of the four sources, this is the one that takes the most value out of the event, so cutting the pantry share is the single change that improves the numbers fastest.
Consumption increase (remainder)	Auto-computed = max(0, 100 - sw - ex - pl)	20% at the opening mix	Counts as net incremental volume, and lasts IF the habit forms. There is no slider for it. The tool fills it in with whatever the other three sliders leave of the 100%. Push those three past 100 between them and the tool warns you in red that the sources add up to more than 100%, and Consumption Increase drops to 0.
Net share of uplift (the main card's large figure)	0% to 100% while the three sliders add up to 100% or less	65% in the opening mix, amber (the PDF grades it MIXED)	The summary metric: net incremental volume divided by the uplift, or of the extra units, the share that was genuinely new. Colored green at 70% or higher, amber from 50% up to anything below 70%, red below 50%, as rules of thumb, with a line under it saying what the band means. When the three sliders add up to more than 100%, it loses its color and the line says the split cannot be read. Put it next to the Category Expansion share and the two together decide which of the four SoV quality bands the PDF gives the event.
Event margin and Durable value tiles	Negative to positive (Durable Value always at or below Event Margin)	Event Margin +$3,840, Durable Value +$1,561 in the opening mix	The Event Margin is the cash the event earns while it runs. The Durable Value takes the same cash, scales each source down by how much of it outlives the promotion, and then takes off the pantry cost. A wide gap between the two means the event is banking cash that will not last. Both figures carry a minus sign when negative. A negative Durable Value means the event destroyed value even though total volume went up, and the Value impact waterfall then draws its total bar in red.

5.3Step-by-step exploration

7-step guided exploration of the scenario.

Read the default settings, a MIXED event that still makes money
Leave every control at default. Read the main card's five figures, then find the dominant source in the Volume source breakdown chart.
Expected outcome: Switching 3,000, Expansion 1,500, Pantry 3,500 (dominant), Consumption 2,000. Net incremental volume 6,500; Unproductive 3,500. Net Share of Uplift 65% (6,500 / 10,000), in amber, with the line "Borderline: 50% up to just below 70%, on the rule of thumb." The downloadable PDF grades this MIXED. Event Margin +$3,840, but Durable Value only +$1,561, about 41% of it, because most of this volume is switching (which counts at 0.25) and pantry loading (which counts against you). Both numbers come out positive, so the event banks cash on its uplift. Both count the uplift only: the 50 cents you also fund on the 5,000 baseline packs sold on deal in the event's one week, $2,500, sits on TPO Lesson 1's bridge, and with it the opening mix keeps $1,340 while it runs and loses $939 once durability is weighed. But Durable Value sits well below Event Margin, and 35% of the uplift was pantry loading, so most of the cash the event banked will not last.
Find the dominant source and understand why it matters
Read the units line under each of the three sliders and on the remainder card (Switching 3K, Expansion 1.5K, Pantry 3.5K, Consumption 2K), or the four bands of the Volume source breakdown chart. The largest is the 'dominant source'.
Expected outcome: Pantry Loading is dominant at 3,500 units (35% of total). That is the biggest economic problem in this event. Pantry volume creates no new demand; it pulls forward sales you were going to get later anyway. When pantry loading is the largest source, it tells you who took the offer. This mechanic, 50 cents off at a featured price, was picked up mostly by shoppers who already buy you, stocking up while it was cheap. The trade plan is paying a discount on a purchase that would have happened anyway, only later.
Shift toward GOLDEN, where the retailer grows too
Drag Switching to 0%, Expansion to 50%, Pantry to 0% (Consumption auto‑fills to 50%).
Expected outcome: Expansion 5,000 + Consumption 5,000 = net incremental volume 10,000. Net Share of Uplift 100% AND Expansion share = 50% of total uplift (well above the 25% GOLDEN threshold). Event Margin = 10,000 x $0.86 = $8,600, and because almost all of it survives, Durable Value is $7,740, close behind. The Net share of uplift reads 100% in green, and the downloadable PDF grades the event GOLDEN. This is what Trade Promotion Optimization (TPO) is aiming at: a shared gain, an event where the retailer and the manufacturer both come out ahead. The retailer's category grows, you gain share, and the margins hold up because there is no pantry cost coming off the total.
Force the UNPRODUCTIVE verdict, the event that destroys value
Drag Switching to 0%, Expansion to 0%, Pantry to 70% (Consumption auto‑fills to 30%).
Expected outcome: Pantry 7,000, Consumption 3,000. Net incremental volume 3,000, a Net Share of Uplift of 30%. Event Margin = 3,000 x $0.86 - 7,000 x $0.50 = -$920 (negative). Durable Value is worse still at -$1,436, because even the 3,000 consumption units are weighted 0.8. The Value impact waterfall draws that total bar in red. The Net share of uplift reads 30% in red, and the downloadable PDF grades the event UNPRODUCTIVE. The event raises total volume on the surface but destroys value underneath. This is the classic pantry‑loading trap, and events shaped like this one are why 'over one‑third of promotions show negative net uplift after cannibalization'.
Test the switching‑only hypothesis, PRODUCTIVE but NOT GOLDEN
Reset. Then drag Switching to 80%, Expansion to 0%, Pantry to 0% (Consumption auto‑fills to 20%).
Expected outcome: Switching 8,000 + Consumption 2,000 = net incremental volume 10,000. Net Share of Uplift 100%. The Event Margin = 10,000 x $0.86 = $8,600, exactly the same event cash as Step 3's GOLDEN case, but the Durable Value is only $3,096, well under half of GOLDEN's $7,740, because switching is weighted 0.25 (switchers rarely stay). The Net share of uplift reads 100% in green, as in Step 3, but the downloadable PDF grades the event PRODUCTIVE rather than GOLDEN, because Category Expansion contributed 0% of the uplift. The event cash is identical to the GOLDEN case, but far less of it survives, and you walk into the retailer with a much weaker story. Switching wins share off a competitor without adding anything to the category, a brand gain rather than a shared one, so the category manager looks at their own numbers and sees no new shoppers.
Scale test, does 2.5x the volume deliver 2.5x the value?
Reset. Drag Total promotional uplift from 10,000 to 25,000 (2.5x the base). Leave the mix at default (30 / 15 / 35, Consumption 20).
Expected outcome: Switching 7,500; Expansion 3,750; Pantry 8,750; Consumption 5,000. Net incremental volume 16,250 (Net Share of Uplift still 65%, the mix is unchanged). Event Margin = $9,600 and Durable Value = $3,902.50, each exactly 2.5x the 10K case ($3,840 and $1,561). Both scale LINEARLY with total uplift IF the mix is held constant. The leverage is in shifting the mix, not in chasing more uplift at the same mix.
Connect this back to the Net Incremental Profit Bridge and the Pricing lessons
Open the related concepts linked from this page: Promo ROI, Promo Baseline, Promo Mechanics, and the Ten Levers of Trade Promotion ROI. Then run the Promo ROI Calculator on the same numbers and compare what it tells you.
Expected outcome: By the end you know which question each tool answers. This decomposer is the diagnosis. It tells you WHERE the volume came from. The Promo ROI Calculator does the money side. Feed it the mix you just worked out and it builds the Net Incremental Profit Bridge, then hands back one verdict: Scale / Hold / Fix / Cut. The two tools are complementary: SoV explains WHY a promo event scored the way it did on Promo ROI; Promo ROI quantifies the dollar impact of the SoV mix. One link back to the Pricing module. Every trade dollar competes with keeping it, and Pricing Lesson 1 says how much that dollar matters on a thin margin. Of the four sources here, Category Expansion is the one whose profit lasts in full after the deal ends. Everything else is borrowing from competitors, from future purchases, or from habit‑elasticity that may not stick.

5.4Reading the output

Every KPI, the formula behind it, and how to interpret a positive or negative value.

KPI	Formula	How to read it
Net incremental volume	Switching + Expansion + Consumption	The part of the uplift that is genuinely new for your brand, either new demand (Expansion), stolen competitor demand (Switching), or durable habit change (Consumption). In full it is uplift minus cannibalization, store switching and the dips before and after, plus any halo; this tool has no cannibalization or store switching slider. The numerator of the Net Share of Uplift.
Unproductive volume	Pantry (loading) only	Units bought now that would have been bought later at full price. Creates the post‑promo dip. It costs 50 cents a unit, the full margin less the promo margin, and every cent of that is money handed to a shopper who had already decided to buy.
Net share of uplift	Net Incremental Volume / Total Uplift x 100	Of the extra units above normal sales, the share that was genuinely new. Green at 70% or higher, amber from 50% up to anything below 70%, red below 50%, rule‑of‑thumb bands matched to the SoV‑quality verdicts (PRODUCTIVE 70% or higher, MIXED 50% or more and below 70%, UNPRODUCTIVE below 50%), with a line under the figure saying what its band means. No color when the three sliders add up to more than 100%, because that split cannot be read. This is the one number to read first, and together with the Category Expansion share it decides the SoV quality verdict in the PDF.
Event margin	Net Incremental Volume x $0.86 - Pantry x $0.50	Every unit of net incremental volume earns the promo margin, and the pantry cost comes off the total. What the promo banks during the event, before any durability discount.
Durable value	(1.0 x Expansion + 0.8 x Consumption + 0.25 x Switching) x $0.86 - Pantry x $0.50	The same cash after each source is weighted for how much survives. It carries a minus sign when negative, and the Value impact waterfall draws its total bar in red; negative means the event destroyed value even though total volume went up. It always lands at or below Event Margin, and it is the number your CFO will judge the plan on.
SoV quality verdict (in the downloadable PDF)	verdict bands over Net Share of Uplift + expansion share	GOLDEN needs a Net Share of Uplift of 70% or higher and Category Expansion at 25% or more of the uplift. PRODUCTIVE needs the 70% Net Share of Uplift alone. MIXED runs from 50% up to anything below 70%, and UNPRODUCTIVE is anything below 50%. The one‑word summary for a review deck. The page itself shows the Net share of uplift and its band; the PDF adds the verdict.
Dominant source	argmax over {switching, expansion, pantry, consumption}	The single largest source by units. When Pantry Loading is the largest source, you are looking at the textbook bad promotion. When Category Expansion is largest, you are looking at the textbook GOLDEN one. Switching and consumption sit in between, and each event has to be judged on its own for how long the volume lasts.

Read the Net Share of Uplift first, net incremental volume divided by the uplift. Below 50%, more than half the uplift was pantry loading, and the event is UNPRODUCTIVE before you look at anything else. Then read the Category Expansion share, because 25% is the line the event has to cross to reach GOLDEN. Then read the Durable Value, which is the dollar outcome that is still there after the promotion. Finally, find the dominant source, the largest band in the Volume source breakdown chart. One word tells you what kind of event you ran: a switching event took share off a rival, an expansion event brought new buyers into the category, a pantry‑loading event pulled sales forward, and a consumption‑building event got households using more. Each one gives you a different story to take to the retailer, and each one holds for a different length of time.

5.55 common mistakes to avoid

Diagnostic patterns that catch the most common misuse of this calculator.

Mistake 1Treating the Event Margin as the only decision metric
Symptom: Take the Step 5 case: switching at 80%, an Event Margin of $8,600, exactly what the GOLDEN event earns, and a Durable Value of only $3,096. The plan is approved on the event cash alone, and in the next planning cycle the category manager at the retailer pushes back hard: "our category did not grow."
Fix: The Event Margin is the manufacturer‑side cash. The Durable Value tells you how much of that cash is still there once the promotion ends, and the SoV quality band in the downloadable PDF (GOLDEN, PRODUCTIVE or MIXED) tells you how the event will land with the retailer. Always use both. A PRODUCTIVE event with a strong Event Margin still puts cash in your pocket. But when the Durable Value comes in low, most of that cash goes again, and there is nothing in the result you would want to show a buyer. Events that keep the retailer relationship strong over the long term need the GOLDEN verdict: Category Expansion at 25% or more of total uplift. You get there by pairing the mechanic with communication, such as a display, sampling and a genuine category claim, rather than a price cut alone.
Mistake 2Confusing the uplift with the net incremental volume left after the post‑promo dip
Symptom: A trade plan claims +10,000 incremental units and gets approved. Look again in Q+1, the quarter after the event, and the baseline had dropped by 3,500 units over the 3 weeks that followed, so the real net gain was ~6,500 units.
Fix: Pantry loading creates a post‑promo dip roughly equal to the pantry‑loaded volume (3,500 units in our default = 3,500 unit dip spread over 1‑4 weeks). The Unproductive volume tile on the main card is your early warning: whatever it reads is roughly the size of the dip you are about to book. Always report net incremental volume (uplift minus cannibalization, store switching and the dips before and after), not the uplift. The Promo Baseline Estimator (Tool #10) measures that baseline shift for you directly.
Mistake 3Over‑indexing on Brand Switching as 'productive'
Symptom: Brand Switching comes out as the largest source, and the team writes the event up as a win. Then in Q+2, two quarters on, the competitor comes back with a counter‑promotion of its own, the same shoppers switch straight back, and the share you gained is gone.
Fix: Switching is productive ONLY if the switched shopper stays. Whether they stay comes down to two things. First, whether anything gave them a reason to stay, such as the product genuinely being better, or the discount having bought a first trial of something new to them. Second, whether the competitor answers with a counter‑promotion within 4‑8 weeks. When switching is the dominant source, also check how many of the shoppers who bought during the event came back to buy again, and group them by when they first bought your brand. Switching that does not turn into a second purchase is a share gain that lasts as long as the discount did.
Mistake 4Ignoring the Consumption Increase share because 'it's the residual'
Symptom: Trade plan commentary treats Consumption as 'whatever is left' and doesn't design for it. Result: Consumption Increase stays down at 0‑15% of the uplift, and the chance to leave households using more of the product than they did before goes unused.
Fix: Consumption Increase only counts as lasting net incremental volume if whatever made people use more carries on after the promotion ends. Designing for it means picking a mechanic that builds a habit: subscribe‑and‑save, multi‑packs that reward using more, or a claim on the pack that puts the product into a specific moment ('great for lunchboxes'). Most trade plans in fast‑moving consumer goods (FMCG) put very little money behind this one. Events built deliberately around Consumption Increase tend to do better over a full 12 months, even when the Event Margin they post during the event itself is lower than a pure‑switching event would have delivered.
Mistake 5Using the 50‑cent scenario math to make decisions about a 20%-off event
Symptom: Someone plans a 20%-off event on the source mix the tool shows for its 50‑cent default (about 10% off), and the verdict that looked PRODUCTIVE turns out to be MIXED once the real mix comes in, because the deeper cut loaded more into shoppers' pantries.
Fix: The two thresholds hold up reasonably well whatever the discount depth: 70% or higher on the Net Share of Uplift, 25% or more on Category Expansion. The dollar figures underneath them do not hold up, because a different discount depth means a different promo margin on every unit. A deeper discount usually changes the mix in two ways. You get more pantry loading, because shoppers stockpile more at 20% off than they do at 10% off. And the bigger cut may pull in a few shoppers who were not buying the category at all, something 10% off rarely does. The tool fixes scenario inputs at 50 cents off / $0.86 promo margin. To read it for a different discount depth, work out the new promo margin yourself first (the $1.36 a full‑price pack earns you, less what you fund on each pack sold on deal), then adjust what you expect the mix to look like. For a real multi‑depth comparison, cross‑reference the Promo ROI Calculator which lets depth vary.

Related concepts

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Go further inside Trade Promotion Optimization

This calculator is the sandbox slice of Lesson 2: Source of Volume Decomposition. Each of the other 7 Trade Promotion Optimization lessons teaches a complementary concept that sharpens how you read the output above.

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