Pay Per Click Search Engine Text Listings

Which creatives perform best? Long or short?

[Quiche]

Hi all
I am a bit confused about which way the market is going at the moment. Google seems to be steadfast in sticking to shorter PPC creatives (25 characters for title, and 70 total for description), but then I notice they have been testing a longer format too.

Then, Y!SM announce (in December) they are moving from their long-standing 40-character title, and 190-character description to a model similar to Google's.

I can understand Y!SM wanting to move more in line with the market leader, but what's the science behind this?

Which style of creative performs best. Does anyone have any stats they will share with the community about campaigns they have run on both engines re. CTR, conversions etc... I would like to think that this shift towards a shorter creative is based on more than a desire to conform!

Cheers - I look forward to hearing your thoughts.

[1Lit]

Search Engines prefer shorter descriptions because they can (a) pack more adverts into a smaller space and (b) people will have less of an idea what they are clicking on so they are likely to click on more ads.

If ad lengths are longer people will find the right thing easier and so not click on as many ads. Hence the PPCSE makes less money.

[Quiche]

Thanks 1Lit. I kind of get why the PPCSEs might be doing it but I am really interested to see what advertisers think and how it will affect them in terms of performance. Does anyone have numbers which prove how the different styles of ads perform?