Since the tragic death of Google's PageRank, the SEO metrics & signals industry is flourishing, many companies try to fill the gap and create the "ultimate metric" for evaluating SEO value of URLs and domains. People love these metrics, they simplify the world around us and "help" us save time, but it is not without a cost! And what a cost it is. What do you really know about these numbers? Where do they come from? What are their limitations? How accurate they are? Are they reliable? When can we actually use them?
If you haven't asked those questions, you are either an amateur in SEO analyzing or a very naive person, because the answers to these questions reveal the truth about metrics (how non-optimal they actually are).
Before we start talking about the problems with metrics, first let's define and distinguish between macro (domain) and micro (backlink) metrics.
Micro metrics are metrics that given to specific backlinks/URLs and should represent the individual value of the URL.
The most common micro metrics are TF/CF (Majestic) PA (MOZ) & PR (Google).
Macro metrics try to measure the value of a domain as a whole and they usually kind of summation of all the individual backlinks and their micro metrics. Like micro metrics, macro metrics have similar names, and the most common macro metrics are TF/CF (Majestic) DA (MOZ) & PR (Google).
All the metrics, without exceptional are based on backlinks - the building blocks of SEO value. It's very important to remember this simple truth - we use these metrics to measure the specific and overall SEO value of backlinks. As we'll further explain and demonstrate, these metrics often mislead us and not doing their "job".
We'll start with explaining why metrics (micro and macro) are problematic, and after that we'll give tips about when and how we can still use them to our advantage.
Here are some more evidences for the inaccuracy of those metric:
jailbreakyourphone.net - a pure spam domain with spammy backlinks getting relatively high DA/PA/TF/CF:
On the other hand, adomaly.com - great domain that's also related to iphone with great authorized backlinks from forbes.com, appleinsider.com etc. getting very low DA/PA:
texasspecialedlaw.com - spammy domain with spammy and low quality backlinks getting relatively high TF/CF/DA/PA:
g8-g20-youth-summits.org - a very authorized domain with backlinks from places like ed.ac.uk, huffingtonpost etc. with very low TF
In conclusion, we've seen many defects & problems with macro and micro metrics including:
Even if you don't "buy" or believe everything I wrote, but only partially, it's still enough to understand why these metrics are bias and therefore misleading, not reliable and without much of a correlation to SEO value.
What's the right way?
Google doesn't familiar with these metrics, only with the backlinks, this is why the key for properly analyzing a domain (for SEO purposes ) starts and ends with the backlinks themselves.
Macro metrics shouldn't be a factor at all when choosing a domain for SEO. The only time you can have some advantage by using macro metrics is when you filter a huge list of random/unknown domains, in such cases you probably want a quick way to filter out most of the really bad ones and to finally have only few domains to manually analyze. But still you will end up with a list of domains with minimum metrics which tells nothing about the SEO value and in that list still hiding many spammy and low quality domains.
As for micro metrics, we can definitely use them, but it has to be wisely and combined with manual check as well. PR is the most reliable micro metric and has the most correlation with actual SEO value, however it hasn't been updated for very long time (Since Dec 2013), so it's usually been used to assess older backlinks. We can also combine other micro metrics (like PA/TF and also OBL) to get a feeling about the backlink's quality and value, but eventually only when it combined with manual analysis by professional and with an healthy common sense, you can really evaluate the quality of each backlink and therefore the total SEO value.