<CodeSystem xmlns="http://hl7.org/fhir">
  <id value="observation-statistics" />
  <text>
    <status value="generated" />
    <div xmlns="http://www.w3.org/1999/xhtml">
      <p>The narrative has been removed to reduce the size of the distribution of the Hl7.Fhir.Specification library</p>
    </div>
  </text>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-ballot-status">
    <valueString value="Informative" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="0" />
  </extension>
  <url value="http://hl7.org/fhir/observation-statistics" />
  <identifier>
    <system value="urn:ietf:rfc:3986" />
    <value value="urn:oid:2.16.840.1.113883.4.642.1.395" />
  </identifier>
  <version value="3.0.0" />
  <name value="StatisticsCode" />
  <status value="draft" />
  <experimental value="false" />
  <date value="2017-04-03T11:27:53+00:00" />
  <publisher value="HL7 (FHIR Project)" />
  <contact>
    <telecom>
      <system value="url" />
      <value value="http://hl7.org/fhir" />
    </telecom>
    <telecom>
      <system value="email" />
      <value value="fhir@lists.hl7.org" />
    </telecom>
  </contact>
  <description value="The statistical operation parameter -&quot;statistic&quot; -  codes" />
  <caseSensitive value="true" />
  <valueSet value="http://hl7.org/fhir/ValueSet/observation-statistics" />
  <content value="complete" />
  <concept>
    <code value="average" />
    <display value="Average" />
    <definition value="The [mean](https://en.wikipedia.org/wiki/Arithmetic_mean) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="maximum" />
    <display value="Maximum" />
    <definition value="The [maximum](https://en.wikipedia.org/wiki/Maximal_element) value of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="minimum" />
    <display value="Minimum" />
    <definition value="The [minimum](https://en.wikipedia.org/wiki/Minimal_element) value of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="count" />
    <display value="Count" />
    <definition value="The [number] of valid measurements over the stated period that contributed to the other statistical outputs" />
  </concept>
  <concept>
    <code value="totalcount" />
    <display value="Total Count" />
    <definition value="The total [number] of valid measurements over the stated period, including observations that were ignored because they did not contain valid result values" />
  </concept>
  <concept>
    <code value="median" />
    <display value="Median" />
    <definition value="The [median](https://en.wikipedia.org/wiki/Median) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="std-dev" />
    <display value="Standard Deviation" />
    <definition value="The [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="sum" />
    <display value="Sum" />
    <definition value="The [sum](https://en.wikipedia.org/wiki/Summation) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="variance" />
    <display value="Variance" />
    <definition value="The [variance](https://en.wikipedia.org/wiki/Variance) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="20-percent" />
    <display value="20th Percentile" />
    <definition value="The 20th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="80-percent" />
    <display value="80th Percentile" />
    <definition value="The 80th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="4-lower" />
    <display value="Lower Quartile" />
    <definition value="The lower [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="4-upper" />
    <display value="Upper Quartile" />
    <definition value="The upper [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period" />
  </concept>
  <concept>
    <code value="4-dev" />
    <display value="Quartile Deviation" />
    <definition value="The difference between the upper and lower [Quartiles](https://en.wikipedia.org/wiki/Quartile) 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." />
  </concept>
  <concept>
    <code value="5-1" />
    <display value="1st Quintile" />
    <definition value="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" />
  </concept>
  <concept>
    <code value="5-2" />
    <display value="2nd Quintile" />
    <definition value="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" />
  </concept>
  <concept>
    <code value="5-3" />
    <display value="3rd Quintile" />
    <definition value="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" />
  </concept>
  <concept>
    <code value="5-4" />
    <display value="4th Quintile" />
    <definition value="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" />
  </concept>
  <concept>
    <code value="skew" />
    <display value="Skew" />
    <definition value="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)" />
  </concept>
  <concept>
    <code value="kurtosis" />
    <display value="Kurtosis" />
    <definition value="Kurtosis  is a measure of the &quot;tailedness&quot; of the probability distribution of a real-valued random variable.   Source: [Wikipedia](https://en.wikipedia.org/wiki/Kurtosis)" />
  </concept>
  <concept>
    <code value="regression" />
    <display value="Regression" />
    <definition value="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)  This Statistic code will return both a gradient and an intercept value." />
  </concept>
</CodeSystem>