Half the money I spend on advertising is wasted; the trouble is I don't know which half. - John Wanamaker What is your interpretation on this?
That typically applies to traditional forms of advertising. It is mainly because tracking traditional advertising is so difficult to do. Internet advertising is thoroughly tracked and you can easily see which ads are working an which are not. So, this old quote doesnt really apply to online ads. You might be able to switch the quote up a bit to make it apply to the web by saying, "Half the money i spend on link building is wasted; the trouble is, I dont know which half."