What does the “Correlation” statistic mean?
The correlation coefficient or Pearson’s r is a measure of the degree of linear association existing between two variables. We want to pay close attention to both the direction and strength of the association. A positive correlation is indicated by the absence of a negative sign and means that variables are changing in the same direction. An increase or decrease in one variable corresponds to the same change in another variable. For example, we would expect that the more time a students studies for an exam (x) the higher the exam score (y). A negative relationship is indicated by a minus sign and means that as one variable increases there is a corresponding decrease in another variable. The strength of a relationship is indicated by the numeric value of the coefficient. Coefficients range from 1.0 to 1.0. These values are examples of perfect correlations. In reality most values are found in between 1.0 and 1.0. Correlations of .30 or less (either + or -) are considered weak, .31 – .70
