PPC – The case against Moz’s Domain Authority

PPC - The case against Moz’s Domain Authority


Domain Authority (DA) is a search engine ranking score developed by Moz that supposedly predicts how well a website will rank on search engine result pages (SERPs).

DA scores range from one to 100, with higher scores corresponding to a greater likelihood of achieving higher rankings.

It’s also a problematic metric misused by unsuspecting marketers and abused by bad actors in the industry. Here’s why it’s time to rethink Domain Authority’s role in your SEO efforts.

A metric for ‘an earlier, very different game’

Bill James, the father of Sabermetrics, the advanced study of baseball metrics, has a big problem with the concept of the “error” metric in baseball.

“It is, without exception, the only major statistic in sports which is a record of what an observer thinks should have been accomplished.”

Michael Lewis, author of “Moneyball,” shared how James describes it… 

The error metric was invented for an “earlier, very different game” when “fielders didn’t wear gloves, the outfield went unmowed,” and “any ball hit more than a few feet from a fielder on leave from the Civil War was unplayable.”

Maybe that’s my big problem with Moz’s Domain Authority metric and anything like it, really. The metric was made for an “earlier, very different game” when the world needed extensive lists of popular websites.

Why I’m beating this ‘dead horse’

While writing this article, I showed some early drafts to some of the smartest SEOs I know. 

A few responded, “It’s all valid, but why beat a dead horse?” or “I think everybody already understands this metric is worthless.” 

I wish that were true.

During a recent new business pitch, a prospective client asked about my notes in the RFP about not using Domain Authority as a KPI. 

After I made my points, the prospect said, “That makes so much sense; the SEO agency we’re firing kept reporting on DA going up, but we weren’t seeing any of the other real KPIs in the organic channel increase.”

While I was finishing this article, the marketing platform for content marketers, DemandJump, released a webinar titled “The Death of Domain Authority.”

One can only hope.

During the presentation, Ryan Brock, Chief Solution Officer at DemandJump, presented their data on why Domain Authority is worthless. 

I’ll let DemandJump speak for itself there, but the point is that Domain Authority is still very much a part of the conversation in 2023.

A brief history of Moz’s Domain Authority and its calculations

As part of the research for this article, I looked into the history of Domain Authority to provide some context to the story. 

Sometimes, details get lost along the way, especially when you reach out to the company for the “official line.”

For instance, through my research, I found that Moz’s Domain Authority (DA) was first released in 2006, and back then, the official word was that it was developed by Moz co-founder Rand Fishkin, along with his team of SEO experts. 

However, when we reached out to Moz to verify this, that bit of history seemed to have been lost in the archives. (Ironically, they referred us back to a Search Engine Land article on the matter.)

Initially, the idea behind DA was to provide a more accurate and reliable way of measuring a website’s authority and influence than simply looking at its PageRank, a similar metric developed by Google. 

Early on, Moz’s DA was based on a combination of link metrics such as MozRank and MozTrust, as well as other factors like the age of the domain, the size of its link profile, and the quality of its content.

In 2019, Moz introduced the second version of the Domain Authority algorithm, this time developed by the late Russ Jones. 

Starting with DA 2.0, Moz retired MozRank and MozTrust and started relying more on their own Link Explorer product, a link index that they claim has “over 35 trillion links.” 

According to Moz:

“Domain Authority 2.0 is a neural network model based on a number of proprietary internal metrics – link counts, Spam Score, and complex distributions of links – alongside other more traditional inputs. Together they approximate the quality and quantity of traffic a link might pass.”

One of the interesting things I found in digging through all of this history is that, outside of the occasional mention of trying to build a better metric than PageRank, there isn’t a lot of mention of Google or any other search engine. We’ll talk about that more later.


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Why Moz’s Domain Authority is a flawed search engine metric

Reason 1: It’s at the domain level 

My big problem with Domain Authority has always been that Google’s PageRank was designed to judge webpages, not domains. 

A metric designed to evaluate a domain would be more like Alexa Rank, now owned by Amazon, which is calculated based on a combination of data sources, including the browsing behavior of users who have installed the Alexa Toolbar or Alexa browser extensions.

Yet, right from the get-go, Moz calculates the authority metric at the domain level, even though Google has repeatedly stated that they don’t look at authority, that is, anything to do with their linking algorithm, PageRank, at the domain level.

Seriously, Google, specifically John Mueller, can’t state this fact enough times.

I have a whole collection of screenshots of Mueller telling people that DA doesn’t align with anything at Google that I use during a class I teach at UCLA about “SEO Mythology.”

Before someone jumps in with an “actually” here like they’re debating comic book character origin stories, Google has stated that they do look at some signals at the “domain” level. However, “authority” (i.e., link-based signals) is not one of them.

Years ago, while sitting on a panel with Gary Illyes of Google in Sydney, Australia, someone asked him about Domain Authority, and he replied: 

  • “We don’t use it, and it doesn’t align with anything we have at Google. [Moz’s] Page Authority has the right idea, but it is not exactly the same, obviously.”

Yes, you read that right. If you didn’t know it already, Moz has another “authority” metric called Page Authority. 

It’s still not the same as PageRank, but at least it’s in the same ballpark, and yet, Domain Authority seems to get all the attention at the dance.

Reading some of Jones’s old blog entries, frankly, I think the disconnect came down to a matter of semantics. In a blog post, “In Defense of Domain Authority,” he wrote: 

“If Google uses anything like the PageRank model, then domain level metrics matter, and here is why. The vast majority of links on the web are internal links. That is to say, most links are one link pointing to another where both reside on the same domain. Thus, the flow of link value is largely contained within these clusters formed around domains. The external links which point to any page on a domain are more likely to pass value on to more internal pages than to more external pages. While each individual external link pointing to a page is not itself a ‘domain metric,’ the undeniable outcome of this pattern is that we form a domain metric like phenomena in the process of simply following links through the web.”

Jones wasn’t the first person to say this, and I doubt he’ll be the last, especially after this article hits the web. 

Usually, when I debate about Domain Authority, some variation of the “internal links matter, and that’s what I really mean when I say ‘domain authority'” argument above comes out. 

However, the problem comes back to the fact that Google still says there’s no such thing as a “domain authority” in their book, so the point is moot.

Dig deeper: Google: Don’t worry about SEO tool scores

Reason 2: It’s a weak correlation

TL;DR – Moz’s Domain Authority doesn’t strongly correlate statistically with Google rankings.

This is a bit of a walk, so be patient.

A few years ago, while working on an article for another publication about the misuse of statistical “studies” by various SEO tool companies, the statistician who assisted me, Jen Hood, reviewed a presentation by Rob Ousbey at Mozcon 2019. It covered Ousbey’s theory of how results on Page 1 of search engine result pages are driven more by engagement with those pages than links. 

Wanting to learn more, I reached out to Ousbey’s old boss, Will Critchlow, founder and CEO of Distilled, who offered me another study by a former colleague of Ousbey, Tom Capper, that provided a deeper dive into the material that Ousbey presented back in 2019.

Capper’s slides reference a February 2017 presentation he did on whether Google still needed links. There was also a Moz study, which, I should point out, was five years old in 2017, so we are talking about the original version of Domain Authority here.

From my interview with Hood on this matter:

  • “In this, [Capper] looks at how Domain Authority and rankings relate,” referring to the Moz metric that is the cornerstone of the tool’s inbound link reporting. “He gives the correlation of Domain Authority to a webpage’s Google ranking as 0.001 for positions 1 through 5 and 0.011 for positions 6 through 10.”
  • “This means that Domain Authority is more highly correlated with search engine ranking for positions 6 through 10, but both results are very weak correlations,” Hood paused to make sure I understood.
  • “To put this in plainer terms, for positions 1 through 5 in Google’s results, Domain Authority can be used to explain 0.1% of the variance in SERP ranking. For positions 6 through 10, it explains 1.1% of the variance in SERP ranking,” clarifying her point.
  • “This is held up as proof that Domain Authority doesn’t matter as much for top positions. Yet the correlations for both are so extremely low as to be nearly meaningless.”

During DemandJump’s recent webinar, Brock presented numerous instances of websites with high Domain Authorities whose content ranked horribly compared to other websites with much lower DA scores (sometimes by more than half!).

Shortly after my interview with Hood was published, Jones was among the first to challenge the conclusions. However, I always felt he proved her point further by doing so.

  • “We know that no single potential ranking factor is going to explain the majority of the algorithm.” Said Jones in his response back in July 2020, “Weak correlations are going to be part of any complex system.”

And that’s my point. We’re dealing with a metric that correlates weakly to the one thing it is supposed to correlate to in the first place, or does it?

Reason 3: Domain Authority wasn’t designed to mimic Google

Have you ever seen someone try to drive a nail into a piece of wood with the handle of a screwdriver? It’s terrifying. 

Maybe it’s just because I have a childhood of my grandfather grumbling, “Right tool for the right job, boy!” 

I’m a little sensitive about this sort of thing. This brings me to my next problem with Domain Authority – people use this tool for the wrong damn job. 

According to Jones, the creator of Domain Authority 2.0, “Moz doesn’t claim to have a metric which mimics Google.”

Call me crazy, but why would anybody bother using Domain Authority if it doesn’t mimic Google?

Well, according to Moz’s website: 

“Domain Authority (DA) is a search engine ranking score developed by Moz that predicts how well a website will rank on search engine result pages (SERPs).” 

Or, as Hood puts it: 

  • “Moz claims to have a metric which predicts with some degree of accuracy the likelihood a site will rank based solely on domain-level link metrics.”

However, as we’ve already established, Google doesn’t look at link-based authority on the domain level, so we’re back to where we started.

Not long after our article on shoddy SEO studies was released, Jones clarified in a Twitter conversation with Hood that: 

  • “Moz does not make a claim that Domain Authority established many cause-effect relationships that lead to a specific ranking on Google.”

Domain Authority’s big lie

James’s major complaint with the error metric in modern-day baseball was that it was too easy to avoid. According to Lewis:

  • “The easiest way not to make an error was to be too slow to reach the ball in the first place.”
  • “You have to do something right to get an error,” wrote James. “Even if the ball is hit right at you, then you were standing in the right place to begin with.”
  • “The statistics were not merely inadequate; they lied,” Lewis continued. 
  • “And the lies they told led the people who ran major league baseball teams to misjudge their players, and mismanage their games.”

That’s what’s happening with Domain Authority – it’s lying to people.

I get it. People love to get things down to “one number” to make their lives easier.

But even in baseball, they know they need to look at myriad metrics to help make their decisions, and their dataset isn’t anything near the size of Google’s.

I mean, at this point, Fishkin himself is kind of embarrassed by Domain Authority, and you can imagine what it took for him to get to this “I have become death, the destroyer of worlds” moment after all this time.

Rand Fishkin on Domain Authority

Who is DA hurting, really?

The idea behind DA was to provide a more accurate and reliable way of measuring a website’s authority and influence than simply looking at its PageRank. 

Moz can use the excuse that it’s not their fault that people are misusing their product as a comparison for ranking in Google. 

But just like when a company that makes weed killer finds out their product is giving people cancer, you don’t just shrug and say sorry. You take that poison off the market. 

Look, I get it. They’re not prescribing Thalidomide to pregnant women or ignoring the health hazards of smoking here. 

Still, Moz has a large segment of the SEO industry hooked on a metric in the belief that it aligns with Google’s rankings when it has nothing at all to do with Google’s rankings.

Millions of companies live and die by the Domain Authority metric every day. When it drops, people panic, and sometimes, jobs are lost because goals aren’t met. 

Meanwhile, as we all know, an entire link and domain buying and selling micro-economy exists with Domain Authority as its core metric. The domain name reselling industry alone is a multi-billion-dollar business. 

Given the clandestine nature of link selling, who knows how much money is wrapped up there?

Companies that use Domain Authority as a KPI often find themselves participating in black-hat link-building practices solely to improve their DA score rather than creating a better experience for their visitors. 

Meanwhile, those same companies end up ignoring the real KPIs of their business in favor of what is basically a vanity metric.

Moz is a good company (I actually use it to teach SEO at UCLA). Still, they could stop all this carnage at any time by simply clarifying that Domain Authority has nothing to do with Google or, better yet, doing away with it altogether.

Moz may never take this metric off the table, but at the very least, you can stop using it in your SEO reporting.

Opinions expressed in this article are those of the guest author and not necessarily Search Engine Land. Staff authors are listed here.


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