-
I need some help understanding the results of a study determining outbound links affect search engine ranking.
Posted by on November 15, 2025 at 6:04 pmI'm trying to understand how something so easily done can have such a positive impact on search engine results. I first heard about this in a YouTube video by Edward Sturm. So I did a litle research and found the webpage with the study.
From the webpage
Study – Outgoing Links Used As Ranking Signal
Update: We have rerun this experiment in April 2020 using fresh domains and can confirm the same results. External links remain a ranking factor and good SEO best practice.
We created 10 sites with 300-word articles about the new product. The articles had comparable structures and text length. Keyword positions were in similar locations within the article to keep everything as consistent as possible. The number of mentions of the keywords tracked was identical across all of the sites. All sites shared equivalent code but looked slightly different via CSS changes.
5 out of the 10 sites contained 3 very high authority outgoing links to Oxford University, Cambridge University and the Genome Research Institute
I'll skip to the results
Results:
The results are clear.
Outgoing relevant links to authoritative sites are considered in the algorithms and do have a positive impact on rankings.
We completed the experiment on the 21st Feb 2016. Exactly 5 months after its initiation. The data we accumulated is substantial and one of the challenges we had was to convey it in a way that clearly showed the rate of success. We have decided to do so with two separate graphs for each key phrase.
rebootonlinedotcom/blog/long-term-outgoing-link-experiment/
-
1 Reply
-
There is this guy called David Quaid that recently went onto the Edward Strum podcast.
David explained PageRank was built off the premise of a medical verification system. The more medical professionals verify a medical paper, the more credibility it acquires. Peer review.
There is a company called iMovR, they sell standing desks. The more people saying that their ergonomic stading desks are awesome, the more the PageRank system has to give credence to these statements, irrelevant of their authority.
Quality over quantity.
As long as a website is legit, Google HAS to consider it’s voice (link). Thats why I am of the firm opinion that any link, from a legit website, irrelevant of the relevance, is better than no link.
The plumber can link to the electrician, even if water and electricity shouldn’t mix.
-
1) This experiment was done 5 years ago.
2) It was a very, very limited sample set. 5 sites in the control group and 5 in the experimental group hardly gives any kind of conclusive data.
3) Even if their conclusion were true, this experiment tells you nothing about the magnitude of outbound links as a ranking signal because they used made up words. It was only these 10 sites competing. Outbound links might have a .000001% impact on rankings, but that was all it took for those sites to rank ahead of the other ones.
-
Just wanted to say all my favorite commenters are here, except WebLinkr
Log in to reply.