Page Rank - Doesn't Always Go As Expected

I've been waffling a lot about page rank recently and I've noticed that the more I try to work it out, the less I know!

The theory goes that page rank is inherited from the linking in pages. Take a customer's PR5 website, you would expect all of the pages linked to from the home page to be PR4 - some are, some aren't.

There are 2 pages on the site that are only linked to from 1 other page. That other page is grey barred. So what PR do we expect for them? Well only 1 link each from a grey barred page. Experts will tell you they also will be grey barred. Actually, they are both PR3.

Take also the links directory of that site. Every page points to the resources page - which is grey barred. It in turn points to the actual links pages, which are inter linked but not linked to by the rest of the site. The only way to find these pages are by clicking through the grey barred top level page.

So do we expect the whole links directory to be grey barred? Of course. A lot of pages are - but then they are 'new' so that's right. But there are dozens of links pages that are PR3.

The top level page just has the standard text that's on every links page. The welcome, actual directory etc. So remove this duplicate content and it's an empty page. Somehow, Google has decided to jump that page and give the PR straight to the actual directory pages.

It's looking like to get a good PR you need at least a couple of paragraphs of unique content on the page and linking somewhere above the page from a good PR page. If the content is too similar then it gets ignored. Possibly there's something about other information linked to from that page - I'll have to explore more with my mortgages site that started this off and see where it leads me,