tag:blogger.com,1999:blog-66531278470261149592011-07-08T03:57:51.980-07:00"... a statement about causal or logical connections between two states of affairs ... it is usually necessary to rule out factors which interfere with examining a specific causal relationship ..."Johanhttp://www.blogger.com/profile/01469278815243268408noreply@blogger.comBlogger01100