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The data definitions sheet every client needs

Most arguments about numbers are arguments about definitions nobody wrote down.

What to define

Revenue: gross or net of refunds, with or without tax and shipping.
New customer: first order ever, or first order in a period, and which source decides.
Conversion: which event, counted where, once per order.
Attribution window: per platform, stated as clicks and views.
Currency and time zone: the same in the store, the ad accounts and the report.

Define the ratios

MER, blended CAC and break-even lines, each with its formula.
Which product costs are included in contribution margin, and when they were last updated.

Who owns what

Name the person who can change each definition, on both sides.
Changes need a date and a note, and the history is restated or marked.

Where it lives

On the first page of every report, in a short block, and in the client record.
Reviewed whenever the store changes its checkout, its tax settings or its tracking.

5 min read. Last updated 2026-10-07. Examples use made-up numbers.

This guide in numbers

5minutes to read

3terms explained

4sections

16related guides

Use it as a checklist

Tick items as you go. Your ticks stay in this browser only.

Revenue: gross or net of refunds, with or without tax and shipping.
New customer: first order ever, or first order in a period, and which source decides.
Conversion: which event, counted where, once per order.
Attribution window: per platform, stated as clicks and views.
Currency and time zone: the same in the store, the ad accounts and the report.

Terms in this guide

MER Blended CAC Contribution margin

Keep reading

Measurement

Contribution margin for ecommerce ads

Revenue pays for nothing until the costs of the order are taken away. Contribution margin is the number that tells you how much room the ads have.

6 min read Operations

A weekly client review agenda that stays short

A weekly review earns its place when it ends with decisions. Without an agenda it turns into a tour of dashboards.

6 min read Measurement

Daily, weekly, monthly: what to look at when

Most bad ad decisions are reactions to a number that is only noise at that time scale. Match the number to the cadence.

7 min read Measurement

Blended CAC: what it is and when to use it

When platforms disagree about who deserves credit, blended CAC answers a plainer question: what did a new customer cost us in total?

5 min read Operations

Ad account structure for an ecommerce store

A structure that the whole team can read is worth more than a clever one that only its author understands.

6 min read Operations

A client offboarding checklist for agencies

A clean exit protects both sides. It also leaves the door open for the client to return.

5 min read Operations

Naming across many brands in one agency

The more clients you run, the more a shared naming pattern saves. The trick is letting each brand add its own code without breaking the pattern.

5 min read Measurement

A quality check before a client report goes out

A report with one wrong number costs more trust than ten right numbers earn.

5 min read Measurement

Cohort analysis for ecommerce: a practical setup

A cohort is a group of customers who made their first order in the same period. Comparing cohorts shows whether newer customers buy the way older ones did.

6 min read Measurement

Putting shipping cost into the margin behind an ad

Shipping is a cost of each order, not an overhead. If the margin behind an ad leaves it out, small orders look more profitable than they are.

6 min read Measurement

Subscription and one-time orders in MER: keep them apart

A subscription store can see its MER rise every month without acquiring anyone new. Splitting renewals from first orders keeps the number honest.

6 min read Operations

Handing over a client account to a new account manager

When an account manager moves on, the client should notice only a new name. The handover is a written transfer of open work, promises and known problems.

6 min read Operations

Audience exclusions guide: who to leave out of paid campaigns

An exclusion decides who a campaign does not pay to reach. Without one, a campaign can spend on people who would have bought anyway or who should never see the ad.

5 min read Operations

An agenda for the first client onboarding call

The first call sets the tone for the whole account. A fixed agenda stops it from turning into a tour of the tools and leaves the client with clear next steps.

6 min read Measurement

A plain-language glossary for client reports

Clients who guess what a number means ask the same questions every month. A short glossary, kept next to the numbers, answers them before they are asked.