correlation coefficient

A numerical index of the extent to which two variables are related. When the score is positive (+0.1 to +1.0), it indicates that the frequency of one phenomenon is associated with the frequency of the other. When the score is negative (–0.1 to –1.0), it indicates that a high frequency of one phenomenon is associated with a low frequency of the other. Perfect agreement between two variables is expressed as +1.0. Perfect inverse relationships are expressed as –1.0. A correlation coefficient of 0.0 indicates no apparent relationship.