"I cross checked this data against our Lifestyle data to be sure that we weren't missing the kids of these householders. Our Lifestyle data confirms that the groups that are highly indexed on Google tend to be older (55+) and the groups highly indexed on Yahoo! Search tend to be younger. I mentioned this to my husband and he asked if the Google users spend more online. Good question (he seems to think young people have no money)!...
As you can see Google's relative audience strengths -- i.e., the groups over-indexed on Google.com relative to the online population -- are those that are among the most likely to have spent more than $500 online. This indicates that Google users are more likely to be big online spenders.
This all begs the question: Why?
Why is it that Google users are likely to be older and spend more and the opposite for Yahoo? Is it the blend of services available? The result Hopkins finds of highly-indexed Google users being 55+ seems odd to me. My parents fall into that age bracket and hardly use the Internet for more than the most casual searches. Meanwhile, my peers, ranging from 25 to 40, seem to have adopted more of Google's services than our parents have. So when Hitwise says Yahoo users are younger, does that mean younger than 25? Younger than 20? Are teenagers the biggest users of Yahoo services?
Why would Microsoft want to buy a company that caters to teenagers? Granted, the 18-34 advertising bracket is highly coveted, as younger people are falling into the purchasing patterns they will likely follow for the rest of their lives. But older people, 34-54, generally have more disposable income.
All interesting stuff. What it actually means, obviously, is up to debate. Have at it.