A lot of industry knowledge around search marketing involves understanding investment and response to various keywords.
There's more to learn!
Have your e-mail marketing team conduct a holdout test, for thirty days, among 5% of your e-mail list. At the end of thirty days, measure search demand per customer in the mail group, and measure search demand per customer in the holdout group. The difference (mail minus holdout) is the demand that e-mail drives to search. This allows you to see how much of your search program is caused by e-mail marketing.
If you are a catalog marketer, conduct the same test, over a three month period of time. The difference (mail minus holdout) is the demand that catalog drives to search.
A lot of folks learn that between 20% and 50% of their search program is caused by other marketing activities ... in other words, other marketing activities cause customers to research product (or to type a keyword into Google to get to your website). When this happens, search becomes an important complement to other marketing activities ... without search, conversions in email and catalog marketing may disappear.
So do this simple analysis, and learn how search complements traditional marketing channels!