Just to chime in with some (admittedly slightly biased) stats for PPC:-

http://googleresearch.blogspot.co.uk...-ad-click.html


    1. 81% of ad impressions and 66% of ad clicks occur in the absence of an associated organic result on the first page of search results. All ad clicks in these situations are incremental.
    2. On average, for advertisers who appear in the top rank organic slot, 50% of ad clicks are incremental. This means that half of all ad clicks are not replaced by organic clicks when search ads are paused.
    3. For advertisers whose organic search results are in the 2nd to 4th position, 81% of ad clicks are incremental. For advertisers appearing in organic position of 5 or lower, 96% of ad clicks are incremental.

    Here’s another study which shows that PPC accounts for 64.6% of clicks from searches with high commercial intent, and for product related searches, the number one organic result accounts for just 8.9% of the clicks! – http://www.wordstream.com/articles/google-ads.


    From what I've seen these stats seem fairly close to the truth...