According to Alexa, they gather web traffic statistics from web surfers who have installed the Alexa Toolbar, or from website pages that display an Alexa Widget.
This means, that visitors to your site that do not have the Alexa Toolbar installed will not contribute to your ranking unless you address this by adding a simple to install graphical widget to your website’s sidebar, header or footer. This way, when any of your sites pages is visited a request is made to Alexa’s system to retrieve your site’s current rank and at the same time Alexa will record the request as a qualified visit to your site and your Alexa rank will be adjusted accordingly.
All Alexa ranks are based on the preceding three months traffic data collected and an average trend rank is calculated when comparing this data against all other sites contained in the Alexa database.
The trend rank of any site is calculated according to the following criteria:
1. Reach – the percentage of global internet users who visited the site.
2. Page views- the percent of global page views the website received
3. Page views/user – a calculation of the page views per visitor to the site
4. Bounce rate – the percentage of visitors to the site that closed the site after visiting only a single page.
5. Time on site – an average calculation of the time spent on the site by each visitor
6. Search percentage – the percentage of visits to the site that were referred from a known search engine.
Alexa have recently stated that its toolbar has achieved over 10 million downloads worldwide, but I am unsure as to the duration this claim refers to. I am confident to assume that a very large percentage of toolbars will remain installed are being installed and therefore continue to contribute to the accuracy of the Alexa ranking system. But, this does however highlight the need for webmasters, who wish to gain the best rank possible, to install an Alexa widget on their sites.
Although not everyone in the web development industry believes that Alexa is a reliable popularity ranking system, Alexa (an Amazon company) remains at the forefront of the website ranking world and receives worldwide recognition of this. I recently searched Google with the keyword “website ranking”, and the results were clear. It was Alexa.Com who was at the top of the search results.
In contrast to Google Page rank systems, the lower a site’s Alexa rank number, the higher the rank is. Google operate a system in reverse where a higher number indicates a higher rank. At the time of writing this article, Google ranked no. 1 on Alexa’s Top Sites list, closely followed by Facebook, YouTube and Yahoo.