The following most commonly used kinds of averages are called measures of central tendency. The mode in a distribution of values or scores is the score that occurs most often. It need not fall in the center of a distribution of values. 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.