Rob Bucci19 POSTS

Rob is the founder of STAT. Also, in no particular order: an SEO-obsessed Ruby programmer, data wrangler, snowboarder, gym buff, game nerd, and general adventurist.

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Yahoo! Search is now powered by Bing. But that doesn’t necessarily mean there’s no need to track both.

Back in October, Yahoo! Search announced that they had completed their transition to being fully powered by Bing.

Since then, many people in SEO have assumed that Yahoo! results are now exactly the same as Bing’s. If you rank #5 for the keyword “shoes” on Bing, you should also rank #5 on Yahoo!, right?

We sat down to do some research into the question, and we found some interesting differences between Yahoo! and Bing search engine result pages (SERPs).

  • Global variance
    In most regions around the world, we see up to 10% variance between Yahoo! and Bing SERPs.
  • US variance
    For the US market, SERPs are the most similar, with less than 5% variance.
  • First-page results
    There is generally less than 2% variance for first-page rankings. But beyond the first page, the variance increases quite a bit.
  • Long-tail and uncommon queries
    Variance was generally higher for long-tail and uncommon queries.

What types of differences are we seeing? In addition to the differences in ranking that you might expect, in some cases Bing returns results that are missing completely on the Yahoo! SERPs.

A closer look at one example

For the keyword “castello” in Germany, the top 100 results differed between Bing and Yahoo! in several ways.

First, Yahoo! returns no result from these URLs that are returned by Bing:

  • www.castello.de
  • www.hrs.de/hotels/de/italien/oleggio-castello/castello-dal-pozzo-418492.html
  • uhren.1-2-3.tv/Herrenuhren/DELMA+Castello/?productDetails=913645
  • www.castellodivilla.it
  • www.kreta-ferienwohnungen.de/haus.php?hausname=castello
  • www.castello-ferien.de
  • de.traveleurope.it/castello-di-casiglio/erba.htm

Second, Yahoo! returns different pages for these domains:

  • www.castello.co.at/cafe.html (Yahoo! returns www.castello.co.at)
  • al-castello.net/anfahrt.htm (Yahoo! returns al-castello.net/ristorante.htm)
  • www.castello-dresden.de/academy.html (Yahoo! returns www.castello-dresden.de)

Finally, Yahoo! returns different rankings for a number of domains. In the SERP screenshot below, the blue boxes show results that differ in ranking, and the red box shows a Bing result that is missing from the Yahoo! SERP.

Bing SERP on the left. Yahoo! SERP on the right.
Bing SERP on the left. Yahoo! SERP on the right.

Bing vs Yahoo

Bing SERP on the left. Yahoo! SERP on the right.

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What’s happening here?

If Yahoo! is well and truly out of the search business, it’s unlikely that they are devoting budget and resources to making intentional tweaks to Bing’s results. In fact, it would be typical for their agreement with Bing to specifically prohibit altering the data supplied.

A more likely explanation is that the data Yahoo! is getting from Bing is not as fresh as the results Bing returns natively.

A few days after we grabbed the example above, we pulled up the same SERPs for “castello” in Germany and found that they had become a one-to-one match. A few days after that, we did the same thing and found that they again had variances.

What this suggests is that Yahoo!’s implementation of the Bing API follows a model of eventual consistency.

When a query is made on Yahoo!, the search engine displays the data it currently has on hand, and then later queries Bing to make sure that those results are in sync with Bing’s. The results for that specific query will be the same until Bing updates its rankings, putting Bing and Yahoo! back out of sync.

What does this mean for your SEO program?

Very simply, if you are doing SEO for Bing—especially if you are optimizing for long-tail searches—you cannot expect your efforts to be immediately and consistently mirrored over at Yahoo! Search. There will always be some lag time between Bing updating and Yahoo! updating.

By tracking keywords in both Yahoo! and Bing, you can monitor the impact of that lag time on your own SEO efforts.

The new relationship between Bing and Yahoo! also underlines the importance of massive-scale keyword tracking for the people who specialize in enterprise-scale SEO. With a broad view of your competitive search landscape, you are able to peek behind the scenes at technical quirks and algorithm shifts alike, putting you in a better position to respond quickly to challenges and take advantage of newly emerging opportunities.

Happy optimizing,
Rob & The STAT Team