[Air-l] research on factors driving traffic to web sites

Hi all, I am doing research on factors that drive traffic to political (parties' and caniddates') web sites. Can anyone point me to some previous research in this field, e.g., studies that highlight some key variables that can account for a web site's amount of visitors, page views, etc.? Does not have to be about political web sites (though I could not find any kind of this research on political sites and would be curious to discover there is some), but also on commercial, news, social-networking, or other kinds of sites. Thanks, Cristian Vaccari www.cristianvaccari.it www.comunicarepolitica.it