This is a question that often seems to be lurking in the background of any discussion that compares different marketing tactics. Whenever you read about using “big data” for online marketing, there it is in the background. The implication is that a marketing campaign is like shooting a basketball through a hoop: you set up, take the shot, and then go look to see if you hit the target.
In practice, however, a better metaphor would be a triple-combo shot in a game of pool. You hit one ball, which hits another, which hits another, which tips the final one into the pocket. Much more complicated geometry than the _dunk-swish_ of making a basket. What I mean is that pay per click, display advertising and a firm plan involving social media and quality content will attract considerable traffic to a site if it has been built correctly. But then it is the purpose of the website to turn that traffic into leads, and then it's the business's job to take care of turning those leads into sales.