Retargeting for Klaviyo on Shopify

Showing ads to people who previously visited your site. Here's how this applies specifically to Klaviyo advertising and why causal inference gives you a clearer picture than Klaviyo's own reporting.

What is Retargeting?

Showing ads to people who previously visited your site. For Shopify brands running Klaviyo campaigns, understanding this concept is critical because it directly impacts how you evaluate Klaviyo's contribution to your revenue.

Retargeting	Klaviyo reports	Causal truth
Data source	Klaviyo Ads Manager	GA4 + Shopify (independent)
Methodology	Click/view tracking	Causal inference
Bias	Self-serving (overcredits Klaviyo)	Independent (no platform bias)

Why Klaviyo's view of retargeting is misleading

Klaviyo credits a sale to email if the customer opened ANY email in the attribution window — even if they bought through a Google ad
Post-purchase flows get credit for repeat purchases that were already inevitable — inflating email ROAS by 2-5x
Welcome series attribution ignores that these customers just signed up and were going to buy regardless

How causal inference measures retargeting for Klaviyo

Causal inference separates email-driven purchases from purchases that would've happened without the email
Counterfactual analysis: what would revenue look like if this email flow didn't exist?
Cross-channel Shapley values show email's true role alongside paid channels