We are all Familiar with Alexa Rank When we create sub domain of our site we get same alexa on sub domain for Example : abc.abc.com but when we create blog on blogspot and wordpress we got different alexa for example : abc.wordpress.com or abc.blogspot.com can you please tell me how they measure it.
Alexa Ranking details are rough estimated data and hence it is not so much precise and accurate. However people use to have a average traffic details.
Of course you would get a different Alexa for wordpress and blogspot domains. They are totally different websites, while if you use your OWN website to create a subdomain, the ALEXA rank is the same as your main domain!
Well I somewhat agree with @patco the sites having sub domain like abc.wordpress.com or abc.blogspot.com is completely different site means here the site is over the wordpress or blogspot, this makes it independent site while if you create a subdomain over your own domain i.e. abc.abc.com means here the page rank that abc.com website has is some is going to the abc.abc.com because it is considered as you own site even if it's subdomain. In short you can say abc.blogspot.com comes under different domain while abc.abc.com comes under the same.
Alexa really does pretty rough estimates basing on the usage of their toolbar and web-site plugins some webmasters put on their pages. Their data is more accurate in the top segment, but when it comes to beginner blogs, it has often little to do with reality.
hi my main domain is :http://www.moviemaniaonline.com/and subdomain : http://download.moviemaniaonline.com/ and i paid traffic exchange companies for my both sites and traffic to my subdomain affected my alexa rank.