The uses of the mode are limited, and it is seldom used in research reports as the only index of central tendency. Most of the important tests of significance are based upon the mean. Variability refers to the spread of dispersion of the data. The range - the distance between the highest and lowest scores 2. The variance - the average squared deviation from the mean 3.
Most researchers routinely report the standard deviation of a data set along with the mean.
Sometimes, however, one may find a reference to the variance, which is an important component in many inferential statistical tests. Various symbols are used for the variance and standard deviation. Range, when it is mentioned, is typically reported in conjunction with, not instead of, other measures of variability. Correlation coefficients quantitatively describe the magnitude and direction of the relationship between two variables. Another index that is sometimes used is Spearman's rho.