4.3.2.166 4.3.2.155 CodeSystem http://hl7.org/fhir/observation-statistics

The [mean](https://en.wikipedia.org/wiki/Arithmetic_mean) mean of N measurements over the stated period.

The [maximum](https://en.wikipedia.org/wiki/Maximal_element) maximum value of N measurements over the stated period.

The [minimum](https://en.wikipedia.org/wiki/Minimal_element) minimum value of N measurements over the stated period.

The [number] of valid measurements over the stated period that contributed to the other statistical outputs.

The total [number] of valid measurements over the stated period, including observations that were ignored because they did not contain valid result values.

The [median](https://en.wikipedia.org/wiki/Median) median of N measurements over the stated period.

The [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) standard deviation of N measurements over the stated period.

The [sum](https://en.wikipedia.org/wiki/Summation) sum of N measurements over the stated period.

The [variance](https://en.wikipedia.org/wiki/Variance) variance of N measurements over the stated period.

The 20th [Percentile](https://en.wikipedia.org/wiki/Percentile) Percentile of N measurements over the stated period.

The 80th [Percentile](https://en.wikipedia.org/wiki/Percentile) Percentile of N measurements over the stated period.

The lower [Quartile](https://en.wikipedia.org/wiki/Quartile) Quartile Boundary of N measurements over the stated period.

The upper [Quartile](https://en.wikipedia.org/wiki/Quartile) Quartile Boundary of N measurements over the stated period.

The difference between the upper and lower [Quartiles](https://en.wikipedia.org/wiki/Quartile) Quartiles is called the Interquartile range. (IQR = Q3-Q1) Quartile deviation or Semi-interquartile range is one-half the difference between the first and the third quartiles.

The lowest of four values that divide the N measurements into a frequency distribution of five classes with each containing one fifth of the total population.

The second of four values that divide the N measurements into a frequency distribution of five classes with each containing one fifth of the total population.

The third of four values that divide the N measurements into a frequency distribution of five classes with each containing one fifth of the total population.

The fourth of four values that divide the N measurements into a frequency distribution of five classes with each containing one fifth of the total population.

Skewness is a measure of the asymmetry of the probability distribution of a real-valued random variable about its mean. The skewness value can be positive or negative, or even undefined. Source: [Wikipedia](https://en.wikipedia.org/wiki/Skewness). Wikipedia .

Kurtosis is a measure of the "tailedness" of the probability distribution of a real-valued random variable. Source: [Wikipedia](https://en.wikipedia.org/wiki/Kurtosis). Wikipedia .

Linear regression is an approach for modeling two-dimensional sample points with one independent variable and one dependent variable (conventionally, the x and y coordinates in a Cartesian coordinate system) and finds a linear function (a non-vertical straight line) that, as accurately as possible, predicts the dependent variable values as a function of the independent variables. Source: [Wikipedia](https://en.wikipedia.org/wiki/Simple_linear_regression) Wikipedia This Statistic code will return both a gradient and an intercept value.