Definition: Mean Absolute Deviation

The mean absolute deviation (MAD) of a data set is the average distance between each data value and the mean. MAD is a measure used to describe the variation in a data set.

Definition: Standard Deviation

Standard deviation is a statistic that measures the dispersion of a dataset relative to its mean and is calculated as the square root of the variance. It is computed by determining each data point’s deviation from the mean and then taking the square root of the variance.

Definition: Percentages

"Per cent" means "out of every 100". Percentage figures are derived by dividing one quantity by another, with the latter being rebased to 100. Percentages are symbolized by %. They are particularly useful for making comparisons and studying differences compared to a benchmark or initial value.