Fat Stacks quote from Breaking Bad by Jesse Pinkman

Do internal links help with SEO? Here’s a correlation analysis of my top 25 articles

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Link building on computer screen

I’ll come out and say it.

The following analysis is very simplistic.

But there’s some value in it so I’m publishing it. Take away what you wish, but you have to think about search rankings far more holistically.  The best takeaway is perhaps my effort at analysis will give you ideas for your own analyses.

Several weeks ago, Spencer Haws told me he had developed a plugin that would speed up building internal links.   He’s since launched it. It’s called Link Whisper.  I had the good fortune to be a beta user so I’ve been using it on my sites for several weeks.

Unless you’re new to blogging or never read anything SEO-related, you’ve no doubt read many recommendations that building internal links is good for search rankings (as in SEO).

That’s been fairly common knowledge for years.

I’m never really sure how much any SEO really knows.   As an aside, I’m not even sure at what point people who refer to themselves as SEOs decide they qualify for that title.  I guess it’s self-proclaimed, kinda like Howard Stern’s self-proclaimed title of the “King of All Media.”  If Howard can do it, surely SEOs can do it.

The problem with internal linking is it’s a drag to do.  It’s time-consuming.

I have tens of thousands of published articles across my sites.  Thinking about improving internal linking across all my sites gives me a headache.

It’s not that I’ve ignored internal linking.  I do it and have done it reasonably well for my better content.

However, I’m not nearly as diligent as I should be.  Wikipedia my sites aren’t.

Speaking of Wikipedia, I thought its internal linking guidelines for contributors offered some good tips.

Now that Link Whisper is around, I’m interested in figuring out just how effective internal links are for ranking.  It’s not an easy task to figure out. Any analysis will be far too simplistic because there are hundreds of factors that go into search rankings.

Nevertheless, I gathered some data from my biggest site to see if I could see any correlation between internal links and search rankings.

Here’s the data I pulled:

  • Top 25 articles:  I pulled data from the 25 articles on my biggest niche site (not Fatstacks) based on the last 30 days of organic search traffic.
  • Number of internal links:  I used Ahrefs to figure out the number of internal links pointing to each of the 25 articles.
  • Number of referring domains:  I also wanted to compare internal links with inbound external links so using Ahrefs I checked the number of referring domains to the same 25 articles.
  • Keyword difficulty:  The measure I’m using to assess ranking capability is the keyword difficulty of the main keyword for each of the 25 articles.   I chose this because all 25 articles pull in a lot of traffic and so they rank very well for targeted keyword plus many other related keywords.

I told you this was a simplistic analysis.  However, I think it’s somewhat instructive.

Here are the results:

Correlation chart of number of internal links and keyword difficulty (Ahrefs)

Internal Links and KD of main KW

Each data point is one article for a total of 25 articles.  Data point 1, is the highest search traffic article.  Data point 25 is the 25th highest search traffic article.  I set out the full data set below in a table.

The blue line shows the number of internal links built to each article.  The red line sets out the Ahrefs keyword difficulty for the main keyword for each article.

Is there a correlation?

Perhaps some correlation. It’s not super strong, but there’s something to it.  I think the main takeaway is that internal links are one piece of the SEO puzzle.  In other words, every single top search traffic article on that site has multiple internal links pointing to them.

Correlation chart of inbound external links and keyword difficult (Ahrefs)

I also wanted to see whether there’s any correlation between inbound external links (referring dofollow domains) and keyword difficulty.  Here’s the chart:

Referring domains (dofollow) and KD of main KW

Correlation?  Again, some correlation, especially for the higher keyword difficulty keywords.  I’m not surprised about that – after inbound external links have long been a major SEO ranking factor.

Putting it all together

How about a chart that puts all 3 data sets together?  It gets a little messy, but here it is.

Internal Links, Referring domains (dofollow) and KD of main KW

Give me all the data, please

I know some Fatstacks readers love data and are much more sophisticated at analysis and statistics than me.  For you, here’s all the data.  Knock yourselves out.  However, instead of focusing too much on my data, do this for your sites. If you know your stuff, you’ll probably be able to come up with better analyses than me.

Post# of Internal Links# of Referring domains (dofollow)Keyword Difficulty Score (Ahrefs) of main keywordsMonthly Organic Search Sessions (last 30 days)
1911310,292
22326439,922
381797,058
41813217,049
56436,523
691076,310
71867795,348
85134,937
92211315,169
105364,974
11144394,908
125154,708
1312774,658
141661264,654
1541183,921
161734323,856
176013,781
1814753,670
1995113,672
20402463,627
211413283,737
222739413,608
23104133,488
2413712,899
2510242,971

Some takeaways

1. Building internal links sucks but it’s one SEO process you have full control of and appears to be worth doing.  That doesn’t mean you can fully control the outcome, as in if you build 15 internal links you’re guaranteed to rank #1 in Google, but it is a process you can control and be proactive about.

2. The above analysis is something you can do for your own sites and it may be a worthwhile exercise.  I’m not a big data hound, but I do stuff like this from time-to-time.  I focus my efforts on my best SEO content always striving to figure out what exactly makes that content so successful with search engines.  In other words, it’s well worth spending time analyzing your best search traffic articles to figure out what makes them do so well.  You can assess more than just links – consider keyword difficulty, content length, content concept, is it part of a series of related articles, formatting, media used.  Consider it from many angles and try to replicate it for your other articles.

Save time building links…

If you’re swamped like me but want to improve your site’s internal linking structure, give Link Whisper a shot.  And yes, links built in this article were done in seconds with Link Whisper.


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