The Hewlett-Packard Laboratories in cooperation with the Cornell University have made a study on the relationships of Twitter users. There have been analysed data sets of 309740 Twitter users. The results do show that the average user has made 255 posts which are read by 85 others and that the average user reads the posts of 80 users. Further results about the communication between users is represented at the following article and the paper.

Drawing Twitter Social Graphs

Social Networks that Matter: Twitter Under the Microscope

Directory Sources: Social Web Research