How authority score resists manipulation (data study)

This week Semrush updated our authority score. We wanted to challenge ourselves and build a benchmark that would be the most resistant to spam and manipulation.

We know that all domain authority metrics are imprecise. Nevertheless, we tried hard to conduct a thorough study and compare our new score with similar scores on the market (Moz Domain Authority and Ahrefs Domain Rating*).

Read on to see what we learned from this study! To read more about the update, check this post.

How we tested it

First, we took 24,000 random domains into 10 equal groups based on their Semrush Authority score (2,400 domains with a score of 0-10, 2,400 domains with a score of 11-20, etc.).

Then we checked each domain’s score on each platform (Domain Authority from Moz and Domain Rating from Ahrefs) as well as our old and new Authority Score.

Finally, we looked at how these scores correlated with organic traffic and signs of link spam.

These were the spams we looked at:

• No organic ranking on SERPs (aka 0 organic traffic)
• Unnaturally high % of dofollow domains in backlink profile
• An imbalance between links and organic traffic
• Too many referring domains with the same IP address
• Too many referring domains with the same IP network
• Presence of another domain with an identical backlink profile

While comparing our old and new scores, we found some interesting patterns:

This graph shows two things:

Area 1 (red): Our old formula will normalize many scores to 40

Area 2 (Blue): Our old formula will...