What gets measured gets managed.
Without quantifiable metrics, website optimization (WSO) is a guessing game. But with hundreds of billions of e-commerce dollars at stake, most companies cannot afford to guess. 
With web metrics, you can progressively improve your search engine marketing (SEM) campaigns, conversion rates, and website performance. The results of using these controlled experiments  are more profits, happier customers, and higher return on investment (ROI). The folks at Amazon.com have a saying that nicely sums up the gist of this chapter: "data trumps intuition.” 
Web analysts are a special breed. They’re people who measure everything. They know how many miles per gallon their cars get, the expense associated with each mile, and which routes to take to increase efficiency. According to Jim Sterne, founder of the eMetrics Summit (http://www.emetrics.org), good web analysts are in short supply.
Nevertheless, website owners are awash in a sea of data. With such a surfeit of statistics the variety of metrics available to analyze can be overwhelming. You can use web analytics software such as WebTrends to analyze server log data and provide standardized reports. But how do you choose the best metrics to measure website success? How do you best run controlled experiments such as A/B split tests, multivariate tests, and parallel flights? What is the best Overall Evaluation Criterion (OEC) for your ...