The direction of a correlation is either positive or negative. In a negative correlation, the variables move in inverse, or opposite, directions. In other words, as one variable increases, the other variable decreases. For example, there is a negative correlation between self-esteem and depression. In other words, the higher your self-esteem, the lower your feelings of depression.
Excel Communications was founded in 1988 by Dallas entrepreneur Kenny Troutt as a long distance reseller in the US telecom sector at the birth of telecom deregulation.
R was created by Ross Ihaka and Robert Gentleman at the University of Auckland, New Zealand, and is currently developed by the R Development Core Team, of which Chambers is a member. R is named partly after the first names of the first two R authors and partly as a play on the name of S.