One of the most famous quotes in advertising which most people have heard is:

“Half my advertising is wasted, the trouble is I don’t know which half.”

Never have truer words been spoken. Except… that doesn’t have to be true any more.  One of the great things about online advertising is that, with the right tools, you can work out exactly how effective every single last cent spent is. It’s an advertisers dream! So there’s no need to argue about which online ad is better – Google AdWords, Yahoo! Search Marketing (formerly Overture), or any other type of advertising – one of the other ad networks, direct advertising or whatever.

All you need is a decent web analytics package (hint: Google Analytics is perfect for this, and free) and a bit of time and expertise to set it up and you can work out which ad, often even which version of which ad (eg. which headline) resulted in the most sales. More later…