Paid Search Clicks and Email Marketing

Today's Question:

Question:  If you execute an email mail/holdout test, and you learn that 20% of paid searches stop happening if email marketing is discontinued, what should you do?

1. Spend more on paid search because paid search helps make email marketing look better.
2. Attribute 20% of all paid search demand to email marketing.
3. Measure all paid search demand and paid search clicks and paid search costs associated with the clicks back to your email marketing program, based on the results of the mail/holdout test.

The answer is an easy one, isn't it?

The answer is (3).

And if I ask 100 readers how many actually execute (3) above, I'll find that fewer than 5% do the right thing.

Your attribution work must attribute demand, clicks, and costs back to email marketing, should you learn that email marketing causes customers to perform more paid search clicks.