Bill Slawski at SEO by the Sea has an interesting post which gives an insight into how Google's Blog Search ranks its results. He has come across a patent application by Google which explains some of the ranking factors.
The patent application, 'Ranking Blog Documents', shows how Google ranks blogs according to searchers' queries based upon a combination of relevance and quality scores.
Positive ranking factors include:
- How many blogrolls list the blog - especially from high-quality blogrolls or blogrolls of respected bloggers.
- Links from other sources - including mail and chats.
How well tags are used to categorize a post.
- The number of subscribers to your blog feed - using data gathered from feed readers.
Clicks in search results.
Factors which may have a negative effect on ranking:
- Automated posting - an anti-spam measure.
- Different content between the site and the feed - an indication of a low quality/spam blog.
- The amount of duplicate content.
- Using words and phrases that appear frequently in spam blogs.
- Posts that have identical size.
- Linking to a single web page - "If the number of links to any single external site exceeds a threshold, this can be a negative indication of quality of the blog document."
The location/quantity of ads - if ads are seen in the recent posts of a blog, they could be considered a negative quality factor.