RankBrain: A Study to Measure Its Impact


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RankBrain Hero ImageStudy: Does RankBrain Actually Improve Search Results?

Google made a big splash in October 2015 when they announced the existence of a new ranking algorithm that they call RankBrain. The news broke in this article in Bloomberg. Google made some very limited comments about what it is, and has had little to say since then.

For that reason, we set out to do a study to see what impact RankBrain has really had, and to try and learn more about how it works. Note that we can’t prove that all of what we found was a result of RankBrain, but believe that at least some of the changes documented below are.

Click here to jump straight to the results! (Including a shareable infographic)

Examples of Other Uses of Machine Learning by Google

RankBrain is a machine learning algorithm that learns over time the different ways humans express themselves. It then pre-processes Google queries, translating more difficult to understand ones into a form that the regular Google search algorithm can understand.

There are many other uses for machine learning, but a couple of examples can help you understand some of the types of things that machine learning can do. One such use is in Google News, as you can see here:

Google News Unsupervised Learning

In the above screenshot, the part I circled in red is where they show directly related stories. Google uses an “unsupervised machine learning” algorithm to find those related stories. Basically, the algorithm is able to detect a high degree of similarity, and based on that, it knows that these other two articles are on the same topic.

The second example is one that I learned about when I interviewed Google’s Peter Norvig way back in 2011. He shared with me the story about how they build Google Translate.

Basically, they initially tried to build the product using a more manual approach, but that did not end up working out well. Some of the problems included that most languages have many exceptions, so a rules-based approach was very problematic, and in addition, language is continually evolving.

Instead, they used a machine-learning approach that is much more dynamic, and can handle much more complicated types of problems, such as translations between languages. Instead, they leveraged the millions of examples of real-world translations to build the product.

Example Site in Many Languages

Some Very Basic Language Processing Concepts

What’s interesting about that dialogue with Peter Norvig is that it contains some insight into the problem with the way language processing has been done in the traditional Google algorithms. What it came down to is that keeping up with the rules in translating languages was just too complex. Turns out, this is the case in Google’s traditional query processing.

For example, consider the example of stop words. These are “some extremely common words which would appear to be of little value in helping select documents matching a user need are excluded from the vocabulary entirely.” In other words, when Google encountered a word like “the” in a query or on a web page, they simply ignored it.

This seems like a good rule, as “the” just does not seem that important to the content of a sentence. However, consider the query “The Office”:

TV Show The Office

As you can see, this query can be meant to ask about the TV show. Historically, this is an example of something that would require a manual exception rule to address. Since the show first aired in 2005, the rule was not needed before then, but suddenly a need would have come up as soon as the series started. A more recent example would be the new app “Fixed” which was just funded in this season of Shark Tank.

An algorithm like RankBrain should be able to see the relationships automatically, without requiring any manual adjustment. It would be able to do that by making observations similar to these:

  1. Sometimes the phrase is shown in the middle of a sentence as “The Office” (both words capitalized, which is not a normal use case for these words
  2. Sometimes the phrase is used in conjunction with words such as “TV,” “show time,” “episode.”

These are just a couple of obvious examples of patterns that could be noticed. Another interesting query to consider is “coach”:

Frequency of the Word Coach

When I first hear this word, I tend to think about a sports coach by default. However, some of the time it might mean this:

The Coach Web Page

For this, a machine-learning algorithm might notice its use in the middle of a sentence as “Coach,” or its use in proximity to “bags,” “handbags,” “leather,” “women’s fashion,” etc.

This is where RankBrain comes into play. One of the notable quotes from the video included in the Bloomberg article was: “(Rankbrain) interprets language, interprets your queries, in a way that has some of the gut feeling and guessability of people.” In loose terms, it has a more dynamic ability to adapt to changing circumstances of how language evolves over time.

Dialogues I Had With a Google Spokesperson

Shortly after the news broke, I had a bit of a dialogue with someone inside Google. Here is what transpired:

Eric: Can you let me know if there is a near term plan to expand the use of RankBrain? I.e. in the Bloomberg article, it seems that you indicate that it’s being used in a “very large fraction.” Is the intention to increase that very large faction in the near term?

Google Spokesperson: We don’t have much more specific to share, but we’ll keep testing new machine-learning models and approaches as we go, and when we get improvements in search quality we’ll carefully roll them out. (These sorts of signals usually aren’t restricted to a specific portion of queries; it’s more that the effects are noticeable more for some queries than others.)

Eric: The example in the Bloomberg article (the predator query) was quite interesting, as it seemed to capture the notion of a query where it’s hard to determine the intent. It’s actually hard for humans to parse that one.

There was also the whole discussion of queries that Google has never seen before.

This seems to suggest to me that RankBrain is adding capabilities in parsing natural language queries, and in particular those that are longer and more complex in formulation.

Is that a reasonable interpretation of what RankBrain focuses on?

Google Spokesperson: Yup, that’s fair, though not “parsing” in the traditional NLP [Natural Language Processing] sense (separating subject, verb, etc.), but overall yes.

Eric: Right, parsing is probably not the right word. More like having a better understanding of the overall intricacies and relationships in language, probably based on deep learning from analysis of its use across the web?

Google Spokesperson: Yeah, being able to represent strings of text in very high-dimensional space and “see” how they relate to one another.

What is High Dimensional Space?

In principle, imagine that you analyze all the English on the entire web (note that RankBrain is already operating in all languages). You start by taking all of the known words and converting them into a numerical index. So perhaps the word “Office” is assigned the number 345,675, and the word “office” is assigned 345,674. This step is taken for ease of processing purposes.

Then you start looking at and finding out what relationships these words have with other words across the web. You might consider things like these:

Word Relationships in High Dimensional Space

Note that the above graphic is a major simplification of the level at which this happens. The types of relationships that can be determined this way can be quite complex, as they need to be able to detect scenarios such as a famous female coach, who is often addressed as “Coach” and her going to a party with a leather handbag from the company Coach, and an article about her making a fashion statement.

Example RankBrain Queries Provided by Google

I have heard of two so far. One of these is from the original Bloomberg article:

Example of a Query Improved by RankBrain

Notice that I have added in purple some notes that show the way that the query might be more normally asked. Here is one that I learned from Gary Illyes in the recent Virtual Keynote that I did with him:

Second Example of a Query Improved by RankBrain

Gary had this to say about the query:

Our old query parsers actually ignored the ‘without’ part. RankBrain did an amazing job of catching that and instructing our retrieval systems to get the right results.

Our Study on RankBrain

Did RankBrain actually improve the quality of search results? Did it fulfill its mission to return better results for types of queries formerly difficult for Google’s search algorithm to handle?

At Stone Temple Consulting, we maintain a database of 1.4M query results as a result of the studies we have done on Google’s rich answers. As part of this, we keep a full snapshot of the results.

As luck would have it, we took a snapshot in late June/early July just as Google began to roll out RankBrain (the “Baseline Set”). We went through the query set to determine if we could find some queries that Google didn’t understand in the Baseline set that they appear to understand today.

After reviewing all of these queries, we found 163 queries that fit the following criteria:

  1. The search results shown indicated that Google didn’t understand the query in the Baseline Set
  2. There is, in fact, a reasonable set of results that Google should be able to find for the query

This latter point is an important one, as it’s not reasonable to ding Google for not understanding a query for which there is no decent result. Consider this example:

Example of a Bad User Query

The query is not well put together by the user, so it’s hard to get a great answer for this one. In addition, we found queries where the user question was really easy to understand, but for which there is actually no great result to be found as far as we could determine. We also excluded those from the study.

The Results!

So here is what we found in aggregate:

RankBrain Study Results

Of the queries we found where Google didn’t understand them in the Baseline Set, they improved results 54.6% of the time. That’s a very strong score.

Study: 54% of difficult to understand queries in sample group show improved results after RankBrain.Click To Tweet

Here is an interesting example:

Example of an Improved Result

In the Baseline Set we got results with PDF files about why the Iraqi resistance to the coalition invasion was so weak. Clearly, not a fit. Google now has gotten the idea that “weak” probably relates to security, and shows a much better result in the number one position.

I also broke down the results into categories as follows:

RankBrain Study Category Breakdown

This brings up some questions:

  1. Is Google using RankBrain to impact selection of featured snippet results?
  2. Could RankBrain trigger the delivery of a map where none was shown before?
  3. Is it possible that the main impact of a given query would be an improved search results snippet?

These are all scenarios that we saw in the results I reviewed. My bet is that it does. Look back to the quote from Gary Illyes above: “… and instructing our retrieval systems to get the right results.” That sounds to me like that would feed into any of the Google algorithms for retrieving results.

Last, but not least, let’s look at some language specifics. Here are some of the categories of items we saw Google improve on:

Categories Where RankBrain Improved Results

The improvements we saw may, or may not, have been due to RankBrain. It’s possible that other algorithm changes could have driven some of the improvements. Nonetheless, I feel comfortable saying that at least some of the changes we saw were RankBrain related.

Summary and Impact on SEO

Predictably, one of the most common questions I get asked is how RankBrain will impact SEO. Truth be told, at the moment, there is not much impact at all. RankBrain will simply do a better job of matching user queries with your web pages, so you’d arguably be less dependent on having all the words from the user query on your page.

In addition, you still need to do keyword research so that you can understand how to target a page to a major topic area (and what that major topic area is). Understanding the preferred language of most users will always make sense, whether or not search engines exist. If you haven’t already (hopefully you have!), you can increase your emphasis on using truly natural language on your web pages.

The real impacts of RankBrain are:

  1. An increase in overall search quality.
  2. An increase in Google’s confidence that they can use machine-learning algorithms within the core search algo, which has already likely led to more such projects being launched.

Infographic summarizing this study:

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Rankbrain Impact on Search Study Infographic

Republished with author's permission from original post.

Eric Enge
Eric Enge is a partner at Stone Temple Consulting (STC), which has been providing SEO Consulting services for over 5 years. STC has worked with a wide range of clients, ranging from small silicon valley start-ups, to Fortune 25 companies. Eric is also co-author of The Art of SEO book.


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