Study Finds Google’s Penguin Update Getting Stricter Over Time

A study by Portent, an Internet marketing company, shows that Google’s tolerance of spammy links to trigger a Penguin algorithm ranking drop has declined by 30% since the Penguin algorithm launched.

The study shows that of the 500,000 links found, Google has been steadily reducing its tolerance for webspam. Now, Google is likely to penalize sites with as little as 50 percent suspicious links in their link profiles, whereas 80 percent was required when Penguin first launched.

Portent analyzed about 10,000 links pointing at each of the top 50 sites on the 2012 Inc. 5000 list. They then captured the SEOMOZ and Majestic SEO data for each incoming link. They designed a crawler to score the link as spam based on the page the link is linking to being related to the page the link is coming from. They did this and collected data on more than 250,000 links pointing at penalized sites, and 250,000 links pointing at non-penalized sites.

Here are the results over time:

Of the top 50 websites on the Inc. 5000 list, the data showed:

• 36 out of 50 — have “clean” profiles with less than 10 percent of their links coming from questionable sources.
• A fifth of the sites are found with 11 to 39 percent of their links likely being spam.
• Four websites are clearly at risk of being penalized with at least 40 percent of their links coming from suspicious pages.

The concern here is that Google is becoming less and less tolerant over spammy links in a site’s link profile. The question is, how low will this spam link tolerance go? 40%? 20%? 5%?