On the subject of Toolbar PR, has anyone else noticed that while Google only used to update it every few months (one of its main flaws), in the past few months they seem to be regularly updating it, which IMO makes it a far more accurate indicator of importance than previously…

I think that the most effective thing anyone in SEO can do is know what’s happening in that area of research, understand it, and then see if you can find evidence of it. You might, you might not.

How does Google PageRank work? Not PageRank, Google PageRank? PageRank is a pretty common algorithm now and all sorts of systems use it and its variants. You can’t know what makes up Google PageRank let alone how it works. You can be aware of how the method has developed through the years though.

My feeling is that sometimes SEO looks way too low level for its own good. I agree wholeheartedly with your last statement.

On your thought, cj, re testing, my first career was as a mathematical statistician so perhaps I can state with some conviction that it is extremely difficult to try to backward-engineer a system as complex as the Google search process by doing tests. Simple things can easily be tested re the current state of affairs. For example, how many characters does Google currently seem to index in the Title.

For anything more complex, there are so many factors and so much noise in the system, that it is difficult to do comparable tests. Just remember the ongoing tweaking of algorithms by the Google engineers and the fact that you may get results from any one of the data centers, which may or may not be synchronized with the one you hit the last time. In addition there may be detection of your user-agent that may mean that you get different results from someone else.

In short in trying to spot subtle and complex effects like changing nofollow tags on blogs, which themselves have complex structures, you are facing insuperable challenges IMHO.

People need to stop fussing over how to manage PageRank by cutting off the flow. PageRank hoarding never worked anyway, and PageRank Sculpting has just proven to be PageRank Hoarding by another name.

A pile of poop smells just as bad by any other name.

Essentially, he confirms that for the past year Google has indeed been letting PR evaporate via nofollow links. Additionally he confirms that it is the case for external links as well as internal, so your hypothesis above would seem to be the case (on a simplified level).

This has some rather serious implications, not on internal pagerank scultping (which is ultimately a minor tweak that only SEOs will really worry about), but on external nofollow linking, particularly on UGC like blog comments. A post with lots of comments containing nofollowed links will have a far more diluted PR to ‘give’ its followed links than a post with no comments at all. Expect to see bloggers switching off comments, or at least switching off links within comments, once this becomes common knowledge.

Make sure you also read Rand’s interpretation of all this over at SEOmoz : http://www.seomoz.org/blog/google-says-yes-you-can-still-sculpt-pagerank-no-you-cant-do-it-with-nofollow

Altre considerazioni su URL e link per il calcolo (aggiornato) del PageRank….