Types of Measure

Central Tendency tells you about the centers of the data. Useful measures include the mean (Weighted Mean, Harmonic Mean, Geometrical Mean), median, and mode (Mode, Multimode).

• Harmonic Mean is the reciprocal of the arithmetic mean of the reciprocals. $\frac{n}{\sum_i^n(\frac{1}{x{i}})}$ , where $i=1,2,...n$ and $n$ is the number of items in the dataset $x$ .

• Geometric Mean is the n-th root of the product of all $n$ elements $x_i$ in a dataset $x$. $\sqrt[n]{\prod_i^n x_{i}}$ , where $i=1,2,...n$ and $n$ is the number of items in the dataset $x$ .

Variability tells you about the spread of the data. Useful measures include variance, Standard deviation, Skewness, Percentile, and Range.

Correlation or Joint Variability tells you about the relation between a pair of variables in a dataset. Useful measures include covariance and the correlation coefficient.