Link an order only when the relationship with search is defensible.
Attribution is not a gamble. Every link must be substantiated with sufficiently strong signals and remain within the same store context.
Start with store separation
A click from store A should never explain an order from store B, even if both stores fall under the same account.
Use reliable identifiers
A shared visitor or session identifier is stronger than just time proximity. Determine which identifier was used for the link.
Check product relation
A product click on the same or a demonstrably related product increases the reliability of the attribution.
Respect time order
Click should be in front of the order and fall within the chosen attribution window.
Work with a score or rules
Make visible which signals count and which minimum threshold is needed before an order is attributed.
Save the reason
A textual attribution reason enables control by support, analytics and e-commerce teams.
Don't force anything
In the event of insufficient evidence, the order should remain unattributed. This protects reports from false security.