I am doing a test. I suspect your Alexa Traffic Ranking report will go UP if you have their traffic tool widget installed on your site. The tool uses java script to “count” visits and I think with the tool installed your ranking report will go up- significantly.
I have tried it on several sites and traffic has gone up- way up- every time.
Of course there are other factors involved- if you are reading about increasing traffic and installing reporting tools you are all ready interested in increasing traffic and are more likely to be using other strategies to increase traffic.
I installed widget on this site 3 days ago and traffic went up by 337, 598.
You can see details on my post : How To Raise Your Alexa Tool Bar Rank – Testing on This Site
I have installed on sites and done nothing as well and traffic REPORT went up. Note I say reports go up- whether actually traffic has moved is hard to say. I am not a big believer in ranking reports actually meaning anything- however others ( such as advertisers) use PR and Alexa ranking as a way to gage your sites value.
You can get your own Alexa Traffic Widget here : http://www.alexa.com/site/site_stats/signup