Today's question comes from Blind Five
Year Old in San Francisco, California, who asks, "As Google continues to add social signals to the algorithm, how do you separate simple popularity from true authority?"
OK, this is an interesting question.
Now, there's an assumption about social signals in the first half of this question.
But I want to address the second part of the question, which is how to separate simple popularity from true authority.
We've actually thought about this quite a bit, because from the earliest days, it would get us really frustrated when we'd see reporters talk about page rank, and say page rank is a measure of the popularity of websites.
Because that's not true. For example, if you were to look at sites that are popular-- well, for example, porn sites are very popular.
But people tend not to link to porn sites.
On the other hand, if you take something like the Wisconsin
Real Estate Board, probably not a ton of people go there.
But quite a few people do link to government websites.
And so popularity in some sense is a measure of where people go, whereas page rank is much more a measure of reputation. It's much more a reputation of where people link.
And there is a disparity there, or else porn sites would have the highest page rank, and government sites would be very, very low within our ranking system.
And that's not the way that things work.
We tend to see more links to reputable government websites
OK, so you can separate simple popularity from reputation, or authority.
But now how do we try to figure out whether you're a good match for a given query?
Well, it turns out you can say-- take page rank, for example.
If you wanted to do a topical version of page rank, you could look at the links to a page, and you could say, OK, suppose it's Matt Cutts.
How many of my links actually talk about Matt Cutts?
And if there are a lot of links, or a large fraction of the links, then I'm pretty topical.
I'm maybe an authority for the phrase Matt Cutts.
So it's definitely the case that you can think about not only taking popularity and going to something like reputation, which is page rank.
But you can also imagine more topical, oh, you're an authority in a medical space, or you're an authority in the travel space, or something like that, by looking at extra signals where you could say, oh, you know what?
As a percentage of the sorts of things we see you doing well for, or whatever, it turns out that your links might be including more anchor text about travel, or about medical queries, or something like that.
So it is difficult.
But it's a lot of fun.
We actually have some algorithmic changes that try to figure out, hey, this site is a better match for something like a medical query.
And I'm looking forward to those rolling out, because a lot of people have worked hard so that you don't just say, oh, this is a well-known site, therefore it should match for this query. It's, this is a site that actually has some evidence that it should rank for something related to medical queries.
And that's something where we can improve the quality of the algorithms even more.