You shouldn't consider a PR Prediction tool a scam. It's just an entertainment stuff. I think there is someway to predict PR, yes.. Yahoo usually shows all your backlinks.. If you study some PR0, PR1, PR2... PR10 sites, and see how do their backlinks look like, I belive you can predict something... I'd rather starting the algorythm, by the uniqueness of the domains you are linked from.. I think there is a geometric progression, so that to get a PR1, PR2 is easier, while getting a PR7+ looks harder.. E.g.: If you have a PR4 site, and place an outbound link to a new domain , PR0, this new domain WILL be a PR3 very soon.. BUT if you place a link from 2-3 PR4 sites to your domain, it shouldn't be a PR4 any soon..
Just forgot.. It should take so long to calculate a "complete" PR, because yahoo shows 10 links per page.. If you have 20k backlinks, it will be 2k pages to load, parse and evaluate..
Plus there are too many other factors you can't tell from a backlink count to consider that good advice. The number of other links on the page and the PR of each page alone are enough to make that technique extremely inaccurate at best.
I've seen people forcefully disagreeing about the relevancy issue. It's barely mentioned on wikipedia. Do you have some evidence? Thanks
In its original form PageRank was about the quantity of links and the strength of individual links based on the quantity and strength of links incoming to the documents linking to the document in question and the quantity and strength of incoming links to those linking documents and so on. For some time Google engineers have referred to PageRank in a more encompassing manner. Just read Matt Cutt's archives and you will find examples. The question is whether the modern PageRank formula has expanded to include broader analytical measures that attempt to judge things such as relevancy or is using PageRank as a broad vocabulary term simply part of the Google culture even though the technical reality of such communication goes beyond the actual PageRank formula? Google has stated that they measure over 200 signals to determine their organic ranking. Prior to the most recent Google Press Day the number was over 100 signals. This alone demonstrates that things change, that Google's algorithms evolve. (I know, obvious) What we do not know is how much of this evolution is within PageRank and how much is outside of PageRank. There is an obvious disconnect between visible PageRank, Google's organic rankings, and the way Google employees use the term PageRank in their language. Therefore we can deduce that Google uses more than PageRank to determine organic rankings. What we cannot deduce is how much the modern PageRank formula has changed and, therefore, how much or what parts of Google's relevancy calculations are within PageRank and how much is external to PageRank. When folks say that PageRank is meaningless they refer to the fact that Google's analyzes of web documents extends well beyond the actual PageRank formula. The reality is that PageRank is not meaningless. The signals or variables used to determine PageRank are a very real part of the broader organic rankings algorithm; it's just not the whole algorithm. In fact, if you blind yourself to PageRank and use an aggressive holistic approach to search engine optimization you will both improve your organic rankings for desired terms and increase your PageRank.
In my opinion and from what I have seen from my sites the Toolbar PR is dependant only on link popularity. However you are right, it seems that Googlers refer to another kind of PR most of the times and if I remember correctly I have seen some people call it Topic Sensitive PR (Don't quote me on this or ask where I saw it, I don't remember) that takes into account relevancy. However that's just a theoritical PR about the page's strength in a specific niche or even for a specific keyword. For example for the keyword Webaster digitalpoint may have a Topic Sensitive PR of 8 but for the keyword Loans PR3. That means that it is impractical or even impossible to give a universal PR value that takes into account relevancy. If we are talking about SERPs the actual equation, at least in my mind is quite simple Good SERPs = High Topic Sensitive PR + Optimized content - Spam penalties Obvously the only problem is that each variable has it's own equation.
PageRank is a published formula so there is no speculation about it at all. You can see exactly how it works. Relevancy and all that jazz are not a part of it. PageRank may be just a link popularity score but that score has a lot of meaning which is what Google tends to talk about. But it still doesn't mean other factors apply.