Are your PPC campaigns eating your organic traffic? Google love for you to bid on your brand name in AdWords, but how to you know if you are wasting money on traffic you could have got for free? Of course, to find this out you need to run some sort of test.
I don’t know how you could run a good A/B split test for this because I don’t know how to randomly segment people into the “see’s PPC ad” and “does not see PPC ad” buckets. Without random segmentation our test will not be fair but hopefully we can get a test that is “fair enough”.
We are interested in the incremental value of adding PPC which is the difference in value between the “No PPC” and “With PPC” averages. This is the figure which you need to compare with the cost of your PPC to decided if it is worth running or not.
The idea of incremental value is important here. Just looking at the value of the PPC traffic will almost certainly give you a positive answer because brand clicks are so cheap.