How to sign: a statistic representing how closely two variables co-vary; it can vary from -1 (perfect negative correlation) through 0 (no correlation) to +1 (perfect positive correlation)
"what is the correlation between those two variables?";
Similiar / Same: coefficient of correlation, correlation
Categories: parametric statistic
Within this category: biserial correlation coefficient, multiple correlation coefficient, product-moment correlation coefficient, split-half correlation, tetrachoric correlation coefficient