From the Google CPG blog:
Do online search campaigns lead to in-store sales? Controlled studies we call ‘Online to Store’ experiments prove time and again that they do!
Check out this video for results from large advertisers that tested the effects of keyword targeted products and categories, generic keywords and online coupons.
Highlights include in-store sales lift, return on ad spend (15:1 in some cases) and halo effects on overall sales.
Understanding the effect of search ads on offline sales is a large part of accurately defining the full value of search campaigns, beyond direct conversion. Consider these results and your own online to store testing.
Search Marketing Communications 