Nielson recently reported that Bing had overtaken Yahoo as the #2 search engine in the US.

To anyone who follows search engines, this is pretty remarkable given that for the past several years, Google has owned 65-70% of total searches (in the Nielsen report, 65.1%), and Yahoo and MSN/Live Search (pre-Bing) have been stuck around 17% and 5%, respectively. Then in 2009 Bing was born, and in a scant 12 or 13 months the market share of the combined Bing/MSN/Windows Live Search more than doubles?

On the surface, this looks amazingly successful. And Nielsen specifically points-out that these are true search queries, versus being contextual or link-based searches, in other words searches that the user didn’t enter in a form field and hit “submit.”

Unfortunately, Mr. Nielsen, there’s a bit of trickery at work, and it seems likely to be working to Bing’s great advantage in your search engine reporting.

A week ago, when I first saw the Nielsen research, MSN had a lead article of “Where are they Today?” for past SNL cast members. Clicking that link led to a splash page with a slide show of cast members, and a headline that said “Search:Where Are “SNL” Cast Members Today?” Clicking that link led to a Bing search results page, with the form field pre-populated with the query, “where are snl cast members today,” and a Bing-branded page of search results, just as if I’d entered the search query.

My suspicion is that my “search” just counted in Nielsen’s ratings report. Yet, I never went to Bing and “searched.” I merely saw content I was interested in and tried to click through to the content.

I had noticed this change in content structure some months ago, and wondered if it would come back to haunt MSN.com because the user experience was made worse by nature of the extra clicks required to get to content. Especially when you think you’re clicking an article headline and are prepared for the whole article after the click, to instead get a full page of search results to wade through is a real annoyance. And if you spend any time on MSN.com, you’ll see a lot of this type of content presentation, so it really seemed like a risk.

While it was obvious as a marketing ploy to drive traffic to Bing, I didn’t think they’d get credit for generating searches in the ratings report without users subsequently filling out form fields. Now I’m not so sure.

Not wanting to be unfair, I posted to the Nielsen Wire page to see if they could clarify the situation I’ve just described, and though you’ll see my post at the bottom (Peterbach), it remains unanswered by Nielsen.

Certainly there are lots of ways search engine share data gets complicated, especially with toolbars, and “powered by” API implementations and the like. But the bottom line is this – Bing has certainly not revolutionized searching from a technical or user-experience standpoint, which makes it too remarkable not to question the reported share of market growth after so many years of share stagnation. Until Nielsen weighs in and refutes it, I’d say a portion of their reported growth is the type of involuntary search I happened upon when reading up on past cast members of SNL; not contextual search, but not true user-initiated search either.

KidWithMatches is the personal blog of Pete Eberbach, VP Director of Online Marketing & Technology with St. John + Partners.