It's been tested, and has been listed on popular seach engines. As a designer, it's necessary to learn who is visiting your website. You will need comprehensive statistics and analysis of server logs. There are many web-based statistics counters available. The best can be favorably compared to server logs.
Separate counters are especially useful in analysing traffic on secondary or doorway pages.
WebTrends now offers a free online stats service, featuring their hallmark comprehensive reporting. TOP OF IT Stats aren't something to be checked once a week or month. It's a daily promotion task.