Over on the Rimm-Kaufman Group blog was a report on what Forrester’s Carrie Johnson had to say at Shop.org’s Marketing Workshop.  There are quite a few interesting tidbits, but here’s the pair that blew me away:

Correlation between Google Gross US Revenues to US E-Commerce Growth: .96.

Correlation with Yahoo Display Ad Sales and US E-Commerce Growth: -.04

Now, I understand that Correlation does not imply Causation but at some level when you get directional spreads like this you have to sit up and take notice.

One explanation is this:  e-Commerce sites do not buy any Display to speak of, but we know that’s not true – don’t we?

Other questions:

1.  Another conclusion would be Yahoo matters very little to e-commerce activity.  Sure, less than Google, but to this degree?  If in fact Display enhances Search performance, you would think Yahoo would have more of an effect. Perhaps folks see Display on Yahoo and then Search on Google?  Wouldn’t that be a trip…

That scenario would really provide a whole new twist on the measurement of view-throughs.

2.  Google gross rev’s include AdSense, of course.  So we’re not really comparing PPC to Display here, though one could argue AdSense is more targeted than Display.  So what we are discussing here is the relevance of ads, not PPC versus Display.

3.  Does Yahoo Display include Travel ads triggered by selection of Location?  Auto ads triggered by selection of Model?  Etc.  Etc.  You could argue those ads are really “Search” if you look at it from a behavioral (customer) perspective.

Sure would like to find the source on this, and see what we are actually talking about here.

Other questions you would ask / data you need to make a judgment on this?  How about wild speculations on what this data means, if anything?