Search: Yahoo > Google
Jakob Nielsen made an interesting comment on my comparative study of search engines (on John Battele's blog). He explains that users often scan the first few hits before deciding where to click, as eyetracking studies show (the famous golden triangle). They probably use proximal cues to quickly assess the comparative quality of results.
Following Jakob's suggestion, I've done some more computations on the study results. Firstly, I computed the maximal score given to each screen of 10 results (pink curve), along with the maximal score for the 5 top results (in green) (of course, I averaged on the 70 queries):
The diagram shows that most of the time there is at least one good result on the page. It is interesting to note that Yahoo now takes the lead (it is in a tie with Google when the mean of scores is used). Here are the detailed results:
I then calculated the percentage of result screens that contain at least one hit with the maximum score of 5:
Again, Yahoo is first, with 67.1% of screens containing at least one result graded 5 (only 61.4% for Google). However, if only the upper half of the screens is used, Google has a slight advantage. The Googlers must have heard of the golden triangle!