Summary
Microsoft adCenter emerge as the better Search Engine (Paid Search advertising Platform) – from a visit to sale conversion point of view – above Google and Yahoo.
Looking at a site wide non-segmented
visit to sale conversion rate is almost meaningless, but used properly, it is a fair metric to use in paid search optimization – In my quest to create a set of segmented Paid Search Benchmarks for this metric, I found that
Microsoft appears to be the best converting Search Engine today!

I conducted a study on 15,014,924 visits across multiple global commerce web properties in Q4 2007, with approximately USD 1.2 Million in Paid Search advertising spend (only web properties that actually generated revenue and had SALE actions deployed were included)
The reasoning behind researching Paid Search only and not overall traffic from the individual search engines – Is that we per definition have not only a lot of data noise in organic traffic, but more importantly, that from a conversion point of view, you would be much more likely to compare apples to oranges, as you do not control keywords, creative, landing page etc. (you are most welcome to post further questions about my methodology in the comments)
Average Visit to sale conversion rate from Paid Search
103 – Microsoft
100 – Normalized AVERAGE
088 – Google
076 – Yahoo
Source: 15,014,924 visits across multiple global commerce web properties (Q4 2007)
100 = normalized average Paid Search visit to sale conversion rate
(VisualRevenue.com/blog – Dennis R. Mortensen)

The findings which were exceptionally consistent from web property to web property – consistent as in the order of the engines. I did find that there was a large fluctuation, but in almost every instance the order hold true.
Is this then true for everybody? – Not necessarily! This is not a researched conclusion; but a mass Paid Search visit volume observation.
It is of course a lot more provocative visualizing the result as above, but a better representation would probably be to include highs and lows (distribution) and an indication on the deviation.

As a side note; It was actually a quite different set of conversion rates and much more diverse and unique from site to site, when I looked at other success actions. Actions such as user signups, request further information etc. (comparing or presenting the absolute conversion rates, would of course not makes sense).
Conclusion
Comparing visit to sale conversion rate across search engines, should probably include some sort of search engine base line attitude towards Cost Per Action (CPA) – and not just a direct comparison. Furthermore; it is definitely worth investigating other search engines (even using the same keywords, Creative etc.) – if you are on Google AdWords only!
January 26th, 2008 at 12:52
Great stuff Dennis thanks for sharing. I’d also like to see some research on conversion rates by vertical.
January 26th, 2008 at 13:14
Hi Steve
Thanks a lot. I will keep that in mind if I run another batch!
Cheers and have a great weekend. :-)
Dennis
February 22nd, 2008 at 8:40
Hi Dennis,
Great info, very relevant and important. Now, do you have data on AOL as it compares to the big three? Would be curious to see how their white-label search (Google) cstacks up with conversions.
Thanks!
February 22nd, 2008 at 15:05
Hi Justin,
Good idea. It would actually be fun to see if there is a difference on the same thing in another skin (and I am likely to believe there is) :-)
.. I will try to include AOL next time I play with “engine stats”
Cheers
March 13th, 2008 at 4:32
I found exactly the same! For the jobs market sote in the UK MSN was 3 times more successful in terms of CPA than Google.
March 13th, 2008 at 4:52
Hi Paul,
The only thing we need then – is for MS to gain some traction and get the ability to provide more volume. :-)
Thank you very much for the comment.
Cheers
Dennis
March 18th, 2008 at 3:06
nice info and great web!