The stats library contains a simple Stats class for statistical calculations. It works on lists of Decimal numbers so that the required precision can be obtained.

Stats

Modifier and type	Method
static Decimal	mean(List<Decimal> nums)
static Decimal	geometricMean(List<Decimal> nums)
static Decimal	harmonicMean(List<Decimal> nums)
static Decimal	median(List<Decimal> nums)
static Decimal	lowerQuartile(List<Decimal> nums)
static Decimal	upperQuartile(List<Decimal> nums)
static Decimal	midhinge(List<Decimal> nums)
static Decimal	min(List<Decimal> nums)
static Decimal	max(List<Decimal> nums)
static Decimal	range(List<Decimal> nums)
static Decimal	midrange(List<Decimal> nums)
static Decimal	mode(List<Decimal> nums)
static Decimal	variance(List<Decimal> nums)
static Decimal	sampleVariance(List<Decimal> nums)
static Decimal	standardDeviation(List<Decimal> nums)
static Decimal	sampleStandardDeviation(List<Decimal> nums)
static Decimal	coefficientOfVariation(List<Decimal> nums)

Measures of centrality

mean

Arithmetic mean.

geometricMean

Geometric mean. All values need to be positive, otherwise it does not exist.

harmonicMean

Harmonic mean. All values need to be positive, otherwise it does not exist.

median

Median, considered to be the middle element for odd number of elements, and an arithmetic mean of two middle elements for even number of elements. For example, the median of (1, 2, 3, 4, 5) is 3, while the median of (1, 2, 3, 4) is 2.5.

lowerQuartile

Median of those elements that are smaller than the median. For example, in list (1, 2, 3, 4, 5, 6, 7), the median is 4. (1, 2, 3) are smaller than 4, therefore the lowerQuartile is the median of that list, which is 2.

upperQuartile

Median of those elements that are larger than the median. For example, in list (1, 2, 3, 4, 5, 6, 7), the median is 4. (5, 6, 7) are smaller than 4, therefore the upperQuartile is the median of that list, which is 6.

midhinge

Mean of lowerQuartile and upperQuartile values.

min

Minimal value.

max

Maximal value.

range

Range of all values, which is the difference between max and min values.

midrange

Mean of min and max values.

mode

Value that appears most often in the list. This might not be a unique value.

Measures of dispersion

variance

Variance of values.

sampleVariance

Variance of values corrected for bias.

standardDeviation

Standard deviation of values, calculated as a square root of variance.

sampleStandardDeviation

Standard deviation corrected for bias, calculated as a square root of sampleVariance.

coefficientOfVariation

Calculated as standardDeviation divided by mean.