It’s VERY important to point out that what we see as Webmasters in the Toolbar is TOOLBAR PR – this is NOT the same score Google uses internally. Toolbar PR is a ‘simplification of REAL PR – which is a complex algorithm – and ONE of the ways Google works under-the-hood.
On its own – PR is NOT the be and end all of ranking high in Google.
Here’s a few I have had experience with: Other Tools Most prediction and calculator tools are inaccurate at best, scams at worst. Getting a link from a high PR domain is cool, but only of real use in a PR donation sense if the actual page your link is on has a decent PR (ie is well cited itself) and doesn’t have a hundred other links on there (or isn’t selling links! A page’s high PR might be a good indication of the natural popularity of that page, but often, it’s the result of manipulation.
You’ll find plenty of working fake PR checkers and other tools using Google. Pages on your site which have a grey bar ** be an indication of a potential issue or indeed G might have a problem with OR it can also be a simple sign you’re not linking to pages often enough in the site structure. it might be just a glitch with the toolbar, or the actual original export.
A reduction in real PR however could see less pages on your site being indexed, or your site crawled less often, or less deep – many think.
Think of Google Toolbar PR as ‘an indication of the PR of what your pages might have been ‘some time ago’.
If you focus on your next QUALITY, EDITORIAL link comes from – your real PR will go up, but more importantly, so will the number of visitors you receive from Google (dependant on other factors too, mind you).
It is also possible for an internal page to have a higher PR than the home page.
Likewise – just because a page has no score in the toolbar does not mean a page has no real Pagerank – it can mean that of course, but it can mean other things.
Real PR is not 0 to 10 scale as in the toolbar scores.
PR is ‘donated’ to other pages and is shared by the number of outgoing links on the pages.
In theory, you may get more PR benefit from a PR 3 page with only two outbound links than a Google Page Rank 5 page with hundreds of outbound links.
Google has an internal PR with a MUCH higher resolution. The sensible mantra for beginners should not be to “increase your PR” but rather “get quality sites to link to you” which will have the same effect, and is still important even in 2017.