Google Can & Does Use Historic Data For Search Rankings

How long does it take for changes to your website to affect your search engine ranking? Well, according to Google, it could be a year… Yep, that’s right. A year.

In a recent Google Webmaster hangout, John Mueller dropped this bomb…

“similarly with some of the quality algorithms it can also take a bit of time to kind of adjust from one state to another state. So if you significantly improve your website then it’s not that from one crawl to the next crawl we will say oh this is a fantastic website now. It’s something we’re probably over the course of a year maybe sometimes even longer our algorithms have to learn that actually this is a much better website than we thought initially. And we can treat that a little bit better in the search results over time.”

John Mueller – quoted at

does this ring true? maybe…

There are a few things to be concerned about here. Firstly, could it mean that if Google sees a problem with your site, and you fall in the search engine rankings, it could really be a year before any changes you make to fix the problem have an impact? Google has previously made statements that things like 301 redirects (pointers from old URLs to new locations when things move) need to be left in place for at least a year to fully transfer the value from the old URL to the new.

But, surely it can’t really take a year… can it?

Is it all about crawl budget?

Douglas Adams said that space is “big, really really big”. Well, I wonder what he would have had to say about the size of the Internet. The thing is absolutely massive. Seriously. It’s so big that Google’s crawler now operates limits on how many pages from a site it will index at a time – a value called the “crawl budget”. Technical SEOs worry about crawl budget for big sites; if you’ve got a large site then it’s possible that some (or even most) of it doesn’t get crawled when GoogleBot visits you.

So, perhaps, this one year window is because the full impact of changes to your website won’t be immediately be seen by Google and so won’t take affect. If this were the case though, I would have expect Google to be more honest about it. Crawl budget is something they’ve confirmed exists, so why be secretive about it?

is google broken?

Google has been having increasingly frequent problems with content indexation, most recently in April and then again in June, either losing pages from the index or being unable to add new pages. Google doesn’t offer much, or indeed any, information as to what causes these problems or how they resolve them, but the more frequently happens the more questions there have to be about how stable Google’s search index is.

and if it is… would google even know?

When giving evidence to the UK High Court recently, Vint Cerf described Google’s algorithm as being “almost impossible to understand”…

To make this really clear, we’re starting to introduce neural network mechanisms for machine learning. We’re talking about systems that are almost impossible to understand. We can see their reaction to the training but if you open up the box, it’s a box with a million dials in it that have all been set to some amount. Nobody really understands exactly how those dials got set because of the way training algorithms work. If somebody says to you, “I opened up the box and here is dial number 7,222 and it’s set to 0.08 – what happens if we change it to 0.10?” Nobody knows the answer to that. 

Vint Cerf, quoted at

So, maybe Mueller isn’t explaining how the algorithm is designed… maybe he’s just reporting on what Google’s observations of the algorithm are. That’s a sobering possibility, given how vital Google’s search has become to everyday life for so many people. And it would be the stuff of conspiracy theories… if you didn’t have the Vice President of Google saying almost exactly that to the UK High Court.

So, what does it mean for you?

No matter what the cause, the outcome for website owners and SEOs is pretty simple – if you’re working on organic SEO then you’re playing the long game, and maybe a lot longer than you thought.

  • Changes you make today may take days, weeks, months, or longer to have an impact
  • Any SEO consultant who is promising you quick results isn’t taking into account how long Google themselves say it takes their algorithm to recognise changes
  • A change in your ranking you are seeing today may be a consequence of something you did some time ago, either positive or negative

oh, and one more thing… old domains might be good again

There was once a trend for buying old domains because there was a belief that domain age (e.g. how long ago the domain was registered) was a ranking factor. Google have stated pretty plainly that domain age is not a ranking factor but, if SEO metrics cling to your site for a lot longer than we thought, picking up a domain with some good relevant search engine standing may be a good investment again.

After all, you’ve got at least a year before anything you do to it will make a difference…

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