Internal Site Search Analysis: Simple, Effective, Life Altering!
http://www.alistapart.com/articles/internal-site-search-analysis-simple-effective-life-altering/

Kaushik, Avinash
List Apart, A
2009

Abstract:

Now when people show up at a website, many of them ignore our lovingly crafted navigational elements and jump to the site search box. The increased use of site search as a core navigation method makes it very important to understand the data that site search generates.