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TMAI #480: 🏅 Key KPI: Cost Per Incremental Sale.

Avinash Kaushik <ak@kaushik.net>
October 23, 2025

[The Marketing Analytics Intersect, by Avinash Kaushik] [1]

TMAI #480: KEY KPI: COST PER INCREMENTAL SALE.

[ Web Version [2] ]

A super simple, super impactful, lesson from our team.

The power of being thoughtful in the choice of a KPI, by accounting

for psychology/culture.

QUICK RECAP: SMART SOLVING INCREMENTALITY.

I’ve emphasized that an effective approach for building a culture

powered by incrementality is to break the problem down into three

impactful layers:

1. CHANNEL-SILO INCREMENTALITY.

_What if I turned off all my Google Brand PPC to zero? What is the

optimal investment allocation across ASC Value, ASC Volume, DABA on

Meta? Yada, yada, yada._

You are trying to improve the incremental impact from a single

channel.

The most common methodology is to use CHANNEL LIFT STUDIES (CLS). Most

digital platforms have it built-in, and provide for free!* For your

offline spend, TV, OOH, Radio, you will have to construct CLS – a

little more work, so worth it.

(*at least to their medium and large customers.)

2. XSTACK INCREMENTALITY.

_When we spend $10 million on YouTube, do we need to spend $40 million

on Television? Can billboards build frequency, while I’m spending on

TikTok Consideration ads, to achieve a bigger brand lift? Yada, yada,

yada._

You are trying to improve incrementality across channels. It is

harder, and more rewarding.

The most common methodology is to use LARGE SCALE EXPERIMENTS (LSE).

No platform provides it for free, sadly. You, your agency, sets up

experiments and does the analysis. You can also sign up with a

specialized provider like Measured [3] - they’ve built a whole

exciting LSE platform.

3. PORTFOLIO INCREMENTALITY.

_What if we fired everyone in the Marketing department? Compared

apples-to-apples-to-apples, what’s the incrementality of Google

Search, Meta, Radio, SEO, and SMS?_

Real hard stuff.

You are trying to understand overall incrementality delivered at a

company level by Marketing. You also get the bonus points from me for

identifying incrementality by channels and tactics (for massive

spenders on Mkt). You will earn my love if you build predictive media

budget allocations on top of all that to power truly

incrementality-centric Mkt!

The most common methodology is to build a MARKETING-MIX MODEL (MMM).

Ideally one that uses machine learning algorithms to understand the

ground truth, and measures incrementality as a portfolio (vs. silos,

then “pulled together” as many MMMs do).

In a lovely twist of life, LSEs now help you _Trust, but Verify_ your

MMMs! They help identify how wrong your MMM is (it will always be

wrong, just a matter of degree). Even when 83% accurate, your MMM is

God’s gift to your Marketing practice. Just make sure it is 83. 😊

CONVERSION LIFT STUDIES (CLS) FTW.

I find teams forget the altitude at which MMMs operate (very, very

high). Then they make this critical mistake: They don’t realize most

tactic level improvements will actually come from the most accessible

tool… Channel Lift Studies (CLS).

So, if your budget is big enough please earn my true love by building

a high quality MMM. BUT, first ensure you have a robust practice of

CLS across all digital channels – at the very minimum.

IF you spend lots offline, great, it is time to build offline channel

silo studies to prove the awesome (/no) incrementality of those

channels.

Building MMMs without CLS is like spending all your money on building

the Starship body, without any focus on the 33 Raptor Engines. High

expense, to go nowhere.

KEY KPI FOCUS: CPIS.

Every CLS is an experiment.

You form a hypothesis.

Your platform provider, say Snapchat, has CLS built in. They will take

your hypothesis, identify the optimal audience for it, distribute them

into test and control groups, and run the experiment for you.

[Note: Test & Control groups don't have to be 50:50. Depending on a

number of factors, it can even be 90:10 or, if you are doing something

crazy, 10:90.]

Here's an example of a Channel-silo hypothesis CLS:

Your ads are delivered to the test group. Performance data (sales,

brand lift) is collected across both test and control groups.

When they (Snapchat, Google, Meta, Tmall) have collected enough data

to reach statistical significance of at least 0.9 (ideally 0.95, and

NEVER lower than 0.9), they will present the Channel-silo

Incrementality results.

This is a typical way an Ad Platform will present CLS results:

This does not look so bad. You made a little bit of money. 1.02 ROAS.

But. These are terrible results. It just does not _feel _that way.

You spent $1 to earn an incremental $1.02 in _JUST_ media costs.

You did not include Agency fees, creative costs, and the cost of goods

sold (the product you sold did not fall off a truck). Oh, and you did

not include employee costs. And, there are hidden opportunity costs

from doing this vs. other things.

See... Terrible results.

[Bonus read: TMAI #455: Minimum Acceptable ROAS? 8. [4]]

I want that reality to sink in. Hence, a little psychological trick.

Snapchat, and other platforms, will usually provide you with one more

view of the CLS results that I want you to focus on more.

This one:

Note: Each conversion might have purchased more than one product. For

the sake of simplicity here, I’m going to assume each order just

sold one product.

Armed with this lovely view... Ignore the ROAS, the Incremental

Revenue, because at some deep gut level it does not hit as much as it

should to result in a change of Snapchat strategy/tactics.

FOCUS ON THE COST PER INCREMENTAL SALE. THE $227.

Any Cost KPI often causes leaders to lean-in just a bit more.

It gets them to ask:_ Hey, what was the Average Order Value of those

two hundred odd incremental orders where CPiS was $227?_

That is an excellent question. Did you sell a $90 product at a media

cost of $227?

If it had turned out that I each product I sold had an Average Price

after Discounts and Promotions of $1,500… OMG, I love that the

Snapchat Advertising Cost Per Sale was a tiny little $227. Joy.

Happiness. More budget to Snapchat to find the point of diminishing

returns!!

But, $227 to sell $110 worth?

Whatever the answer, the discussion will hit a little deeper than

saying_ incremental revenue was $53k_ or saying_ the ROAS was 1.02._

Focus on CPiS. Ignore ROAS.

It is a much more psychologically potent KPI.

It will raise good questions, it will facilitate insightful

conversations, it will set higher standards for your internal

Marketing, external Agency, and Ad Platform.

That’s how Marketing becomes a competitive advantage.

THE RISK FROM A FOCUS ON COST.

A focus on efficiency can come at the cost of effectiveness.

Sometimes, you might want to lose some or a lot of money if you can

make a lot of revenue. Say, you are one of these AI start-ups who have

been handed billions of VC dollars, and growth is all that matters.

Be aware of this scenario. Check if it applies to you. If it does,

spend where you can get the most incremental revenue / signups. Costs

be dammed.

If you don't fit in this scenario... Focus on CPiS. From your CLS,

LSE, & MMMs.

BOTTOM LINE.

Culture eats strategy for breakfast.

Hence, my nudge to focus on understanding the psychology of

persuasion. In this instance, powered by using the right KPI.

One of the most amazing things about Conversion-Lift Studies is that

they don’t need to take a massive amount of time, and the analysis

is relatively simple. That means, they power quicker tactical changes

to your channel-level tactics – and they do it on the basis of

incrementality.

Carpe diem.

-Avinash.

PS: Oh, it goes without saying the most powerful thing you are doing

is not running the experiments… It is making decisions, taking

actions! Analysis without actions is a perfectly built Starship that

never flies – a heartbreaking waste of time and resources.

Thank you for being a TMAI Premium subscriber - and helping raise

money for charity.

Your Premium subscription covers one person. It's fine to forward

occasionally. Please do not forward or pipe it into Slack for the

whole company. We have group plans, just email me.

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