One of the main misconceptions those new to PPC advertising have is that where they place their budget is the source of the traffic. In reality, most paid search solutions utilize some syndication sources to increase the total number of searches available. That's pretty much standard practice in the paid search advertising industry. But how does advertising that is syndicated compare to pure search referrals? Efficient Frontier has released some incredibly interesting insights showing where click referrals are coming from and the ROI for each of the big three networks - Google, Yahoo!, and MSN.

Interesting to Note:
You've probably heard advertisers complain that using the content network at Google results in poor conversions, while utilizing the search network alone yields the best results (especially if you understand match types). This seems to hold true based on the chart above.