I've spoken about link building in here on a few occasions as having good quality links to your site impacts Google's view of it and therefore where it places your site in the SERPs for relevant searches.
It's also common knowledge that this measure of a site's importance is being abused as sites buy links purely to gain a better rank in the SERPs. I'm not talking about sponsored links, links bought for click traffic, I'm talking about links bought for link juice.
Many in the industry feel Google is powerless to do anything about this, after all it's very very hard to find out of a link is being purchased or is appearing on merit.
A lost cause? Is Google doomed? Is the internet firmly in the hands of the scamsters? Perhaps not......
Another metric could provide a ray of hope in the quest for an honest and true results page, namely bounce rate. If you use Google Analytics you will be familiar with bounce rate. In simple terms if a person lands on a page of your site from a Google SERP then hits the back button they have bounced off your site.
So let's create a simple scenario. Google's index has decided www.somesite.com/Widgets is an authority on the subject of widgets. It's decided this because the page talks about widgets, the word widgets is in the URL, page title, content etc. Also, Google knows that say 120 sites link to this page with the link text widgets. The engine thinks, 'this site talks about widgets and other sites link to it using the word widget' and gives it page 1 position 1 status. However, Google's powerful stats engine notices that people who follow this link are back on the SERP's within seconds of leaving. Google is saying 'here's the best site we know of on the subject of widgets' but people visiting the site don't agree. The search engine now raises a flag against this site as it realises something isn't quite right.
I'm not going to take this any further just now but there are people out there who believe bounce rate - with suitable filters - could be a powerful measure of the true authority of a site. What does this mean? Like I keep saying, spend more time creating a great site and less time trying to out manoeuvre Google.