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Links as a Google Ranking Factor: A 2019 Study

Posted by EricEnge

Do Links Still Matter?

For the fourth year running, Stone Temple (now a part of Perficient Digital) conducted a study on how much links matter as a ranking factor. We did that using Moz’s Link Explorer and in this year’s study, we looked at the largest data set yet — 27,000 queries.

Our study used quadratic mean calculations on the Spearman correlations across all 27K tested queries. Not sure what that means? You can learn more about the study methodology here.

The major study components included:

  • Total number of links to the ranking pages
  • Moz DA of the links to the ranking pages
  • Moz PA of the links to the ranking pages

Slicing these calculations into several sub-categories:

  • Informational vs. commercial queries
  • Medical vs. Financial vs. Technology vs. All Other queries

We were also able to evaluate just how much the Moz link index had grown for a subset of the queries because we have used the same data on 16K of the 27K queries for three years running (this year’s study looked at 9K more queries, but 16K of the queries were in common). In fact, let’s start with that data:

That’s pretty significant growth! Congrats to Moz on that improvement.

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.

Core study results

Time to dive in! First, let’s take a look at the global view across all 27K queries:

This correlation score comes in at a solid 0.293 score. Considering the complexity of the Google algorithm’s 200+ ranking factors, having one single factor come in at a correlation score that high indicates a strong level of correlation.

Next, let’s take a look at the correlation to Moz DA and Moz PA:

Both DA and PA show strong correlations; in fact, more so than the total number of links to the ranking page.

This is interesting because it does suggest that at some level, the authority of the linking site and the linking page both matter. By the way, in the four years that we’ve conducted this study, this is the first time that the DA and PA scores have been a stronger indicator of ranking potential than the pure link count.

More broadly, from a link-building strategy perspective, this provides support for the notion that getting links from more authoritative sites is how you should focus that strategy.

Finally, let’s take a look at how commercial and informational queries differ:

Now that’s interesting — informational queries show a materially higher level of correlation than commercial ones.

From an interpretative perspective, that does not necessarily mean that they matter less. It may just mean that commercial pages get fewer links, so Google has to depend more heavily on other signals. But should those commercial pages happen to draw links for some reason, the impact of the links may still be as high.


The data still shows a strong correlation between links and rankings. Google’s public statements and its actions (in implementing penalties) also tell the same story. In short, links still matter. But we also see a clear indication that the nature and the quality of those links matter too!

Want more information? You can see the Stone Temple link study here

Tell us what you think — do links matter as a ranking factor?

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The Plain-English Guide to Data Deduplication

Nowadays, with so much critical information saved on our computer systems, we’ve learned to backup data regularly — including our email inboxes, our Word documents, our photos, and entire folders of old work.

It’s typically a ton of data. And, since we usually backup and save our data on auto-pilot, we might not realize just how much has been re-copied and re-saved, time and time again.

Unfortunately, over time, our data storage becomes unnecessarily burdened with redundant copies of data — this could cost your company money, as data requirements become larger, or time, as processing time becomes slower.

This is where data deduplication comes in.
Download 9 Free Excel Templates for Marketers

Andrew Le, an IT Helpdesk Technician at HubSpot, further explains the importance of data deduplication for a business looking to grow — “[Data deduplication] really improves scaling and efficiency when pulling data from one source. If you have lots of the same data in different spaces, your entire system can be slowed down.”

To ensure you’re optimizing your data backup storage, we’ve cultivated a list of the best data deduplication software you can use to minimize unnecessary data copies, today.

Data Deduplication Software

1. HubSpot’s Deduplication Feature

If you use HubSpot’s CRM to manage your contacts, you’ll be impressed to find out you can also use HubSpot’s machine learning-powered deduplication feature to keep your contact database clean. HubSpot contacts can be deduplicated by a usertoken set with a cookie in their web browser or email address — additionally, contacts, companies, deals, and tickets can be deduplicated using a unique object ID.

2. Barracuda Backup Deduplication

With a 9.1 user rating out of 10 on TrustRadius, Barracuda Backup is a good option, offering a robust, secure, fully-integrated data deduplication solution. Their tool can help your business reduce bandwidth requirements and backup costs. Additionally, Barracuda is a good option if your business needs to protect multiple sites, since its cloud storage technology helps distributed networks stay protected.

3. Avamar

Avamar, a solution from Dell EMC, provides variable-length deduplication, which reduces backup time by only storing unique daily changes while simultaneously maintaining daily backups. Avamar is an efficient, secure option and is particularly useful for virtual environments, remote offices, and enterprise applications.

4. HPE StoreOnce

HPE StoreOnce, a solution from Hewlett-Packard Enterprise, offers disk-based backup, deduplication, and secure long-term data storage. Their deduplication software is equipped for virtual backup machines in small remote offices, and equally capable of handling high-performance dedicated applications for larger businesses. Ultimately, this is an impressive tool to help you keep your data secure and efficient as you scale-up.

5. Exagrid EX Series

Exagrid implements a highly efficient approach to data deduplicaton that allows six times the backup performance, and up to 20 times the restore and VM boot performance. With Exagrid, you can backup your data straight onto a disk without inline deduplication processing, enabling a shorter backup window.

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