Why Does Google Display Page Rank?

Why does Google periodically make available its page rank? And why does it seem to coincide with major changes?

Page rank is being constantly updated. If you assume that pages are always displayed in an order based on page rank (and other factors of relevance) then by displaying all pages in a site (using site:) then all pages should be shown in page rank order.

To test this, I need to view a site immediately after a page rank export – but this assumes that page rank hasn't been exported from an old version… But it would be a good indicator.

So try it now on your site – do all pages appear in PR order – a few weeks after the recent changes. Probably not. This would imply that Page Rank has been updated since – but not exported. And this is what is supposed to happen – the export just gives us an idea of what is going on, not the actual hard values that are used.

So why? It generates far more traffic to Google in looking up the values for every page you open. It means they need a copy of the PR database for the public view (given they are not making actual values public). They need to maintain and update this system.

First and most obvious is that our browsing behaviour is reported to Google. It can track which pages are in use and popular in sites. But when popular sites drop from results, this isn't a major factor.

So what else can they be achieving? And is it me, or do they always export after major changes to the listings? Are they making the data available so that the real world then sees what's going on, have a guess at what took place and start to complain at what we see as unfair results within this – sites missed and sites unfairly hit?

That would then give them chance to refine their algorithms and make corrections. And it would be far easier than have a team of people sitting their trying to monitor millions of sites and the resultant changes!