Which email marketing attribution method should you trust?
The short answer
Campaign rankings can flip with the attribution method, so email marketing attribution should always state which one it used. Last-click credits the final touch, multi-touch splits credit across touches, and a holdout test measures revenue the campaign added against a group that never received it. Report the holdout figure wherever you can run one.
Why it matters
Attributed revenue drives budget, so a method that over-credits email moves spend toward campaigns that only caught purchases already on the way. Knowing what each campaign added protects margin on discount-heavy sends and funds the ones that grow sales.
The question to ask
Copy this into Lexi as written.
How to work it out
1. Pick a window and a method. Set one attribution window, such as seven days after a click, and record the method used in every campaign report.
2. Run the same campaigns through each method. Compare last-click, multi-touch and, where you have one, a holdout group for the last 90 days of campaigns.
3. Check who bought. Split attributed buyers into customers who were already due to buy, based on their usual purchase gap, and customers who were not.
What the answer looks like
Illustrative output on sample data
Illustrative example: how Lexi answers this for a footwear retailer. It credits revenue from three email campaigns in the last 90 days using three attribution methods.
- Spring launch: $182,000 last-click, $121,000 multi-touch, $64,000 incremental against a holdout
- 20% off weekend: $240,000, $198,000 and $31,000
- Running shoe replenishment: $58,000, $49,000 and $41,000
What the data shows
On last-click, the 20% off weekend wins. Against a holdout it added the least, because most buyers were already due to purchase and took the discount.
What it means
The replenishment campaign is the smallest on last-click but keeps about 71% of its revenue as true lift.
What to do
Expand replenishment emails and cut the discount weekend back to customers who only buy on offer.
Holdout figures need a large group to be stable, so start with your biggest sends. Want me to set up a holdout on the next campaign?
Frequently asked questions
What is email attribution?
Email attribution assigns revenue to the emails that influenced a purchase. Methods differ in how much credit email gets. Last-click gives all of it to the final click, multi-touch shares it with other channels, and holdout testing counts only revenue above what a group that received nothing went on to spend.
Why does last-click attribution flatter discount emails?
Discount emails reach many customers who were going to buy anyway, and the code gives them a reason to click first. Last-click then credits the email with the whole sale. A holdout group reveals how many of those purchases would have happened without the email, often at full price.
Which attribution model should retail campaigns use?
Use a holdout test to decide whether a campaign type is worth running, and a consistent last-click or multi-touch model for day-to-day comparisons. Holdouts measure real lift but need large sends. Whichever model you pick for routine reporting, apply it to every channel so email and paid media compete on equal terms.