How to Tell If a CPG Promotion Actually Worked

(And why most brands get it wrong)

Promotions are one of the biggest investments CPG brands make and one of the hardest to evaluate correctly.

A promotion might look successful on the surface. Volume goes up. Shipments increase. The report says “+20% lift.”

But did it actually drive growth?

For many brands, the honest answer is: they don’t really know.

Why promo performance is so easy to misread

Most promo analysis focuses on a single question:

Did sales go up during the promotion?

That’s the wrong question.

Sales almost always go up during a promo. The real questions are:

• Was that lift incremental?

• Did it just pull volume forward?

• Did velocity fall after the promo ended?

• Did margin erosion outweigh the gains?

Without answering these, you’re not measuring performance, you’re guessing.

The three things every promo analysis should include

1. Incrementality, not just lift

Promo lift tells you what happened during the promo.
Incrementality tells you what wouldn’t have happened otherwise.

A promotion that increases volume by 20% but cannibalizes future weeks may deliver far less true growth than expected.

Ask:

• How does promo-period velocity compare to baseline?

• What happens in the weeks immediately after?

2. Post-promo behavior

One of the most overlooked signals is the post-promo dip.

If velocity drops below baseline after a promotion, the “success” may simply be borrowed demand.

Ignoring post-promo behavior leads teams to repeat promotions that look good on paper but quietly hurt long-term performance.

3. Retailer and SKU-level differences

Promotions don’t work uniformly.

The same promo might:

• Be incremental at one retailer

• Be fully subsidized at another

• Work for one SKU but not the rest of the line

Looking only at rolled-up results hides these differences and leads to blunt decisions.

Why this analysis rarely happens consistently

Most sales teams know they should look at all of this but they don’t.

Why?

• The analysis is manual

• Data lives in multiple places

• By the time insights are ready, decisions are already made

So teams default to simplified metrics and move on.

What better promo decisions look like

High-performing CPG teams:

• Evaluate promotions in context, not isolation

• Understand which mechanics actually drive incrementality

• Adjust duration, depth, or timing based on real behavior

• Learn continuously instead of repeating the same playbook

This requires always-on analysis, not one-off reports.

Where tools like Scout come in

This is exactly the type of analysis Scout automates.

Instead of rebuilding promo reports after the fact, Scout continuously evaluates lift, incrementality, and post-promo behavior as the data is available, so teams can make smarter decisions before the next promotion.

Final thought

Promotions shouldn’t be a leap of faith.

With the right analysis, they become a learning engine one that compounds growth instead of quietly eroding it.