Many folks I think ask wisely, “Are links still that important to Google? It seems like the search engine has grown in its understanding of the web and its capacities.” Well, there is some pretty solid evidence that links are still very powerful. I think the two most compelling to me are, one, the correlation of link metrics over time.
So like Google, Moz itself produces an index of the web. It is billions and billions of pages. I think it’s actually trillions of pages, trillions of links across hundreds of billions of pages. Moz produces metrics like number of linking root domains to any given domain on the web or any given page on the web.
metric called Domain Authority or DA, which sort of tries to best replicate or best correlate to Google’s own rankings. So metrics like these, over time, have been shockingly stable. If it were the case someday that Google demoted the value of links in their ranking systems, basically said links are not worth that much, you would expect to see a rapid drop.
For the past few years, Stone Temple Consulting, which was acquired by Perficient, has come out with a study analyzing just how important links are to rankings in Google search. Year after year, the study shows that having good quality links to your site has a high correlation to your site ranking well in Google search.
This year it is no different.
Stone Temple published the 2019 version of the study that shows a very significant correlation between links and ranking position in Google search.
Brief commentary on correlations
Correlation studies attempt to measure whether or not two factors are related to one another in any way. We use correlation studies to help us understand whether or not one factor potentially causes the other It’s important to understand that correlation does not prove causation; it simply suggests that it does.
The example I like to share is that there is a strong correlation between the consumption of ice cream and drowning. That does not mean that one causes the other. In fact, the causal factor here is intuitively obvious — hot weather. People eat more ice cream and people do more swimming when it’s hot outside.
But, in the case of links, we also have the fact that Google tells us that links still matter. If that’s not enough for you, Google still penalizes sites for questionable link-building practices. This is not an area they would invest in unless links matter.
So how do correlation scores work?
A correlation score scale runs from -1 to 1. A score of 1 means a perfect correlation between two items. So if we have two variables (x and y), whenever x increases in value, so does y. A score of -1 means the exact opposite: whenever x increases in value, y decreases in value. A score of 0 means there is no perceivable relationship whatsoever. When x increases in value, y is equally likely to increase or decrease in value.
Search is a complex environment to evaluate. Google claims to use over 200 ranking factors. Therefore, it’s quite unlikely that any one factor will be dominant. High scores are not likely to happen at all and correlation scores of 0.2 or higher already start to suggest (but not prove) the existence of a relationship.