{
  "resourceType": "CodeSystem",
  "id": "observation-statistics",
  "meta": {
    "lastUpdated": "2019-11-01T09:29:23.356+11:00"
  },
  "url": "http://terminology.hl7.org/CodeSystem/observation-statistics",
  "identifier": [
    {
      "system": "urn:ietf:rfc:3986",
      "value": "urn:oid:2.16.840.1.113883.4.642.4.1126"
    }
  ],
  "version": "4.0.1",
  "name": "StatisticsCode",
  "title": "StatisticsCode",
  "status": "draft",
  "experimental": false,
  "date": "2019-11-01T09:29:23+11:00",
  "publisher": "HL7 (FHIR Project)",
  "contact": [
    {
      "telecom": [
        {
          "system": "url",
          "value": "http://hl7.org/fhir"
        },
        {
          "system": "email",
          "value": "fhir@lists.hl7.org"
        }
      ]
    }
  ],
  "description": "The statistical operation parameter -\"statistic\" codes.",
  "caseSensitive": true,
  "valueSet": "http://hl7.org/fhir/ValueSet/observation-statistics",
  "content": "complete",
  "concept": [
    {
      "code": "average",
      "display": "Average",
      "definition": "The [mean](https://en.wikipedia.org/wiki/Arithmetic_mean) of N measurements over the stated period."
    },
    {
      "code": "maximum",
      "display": "Maximum",
      "definition": "The [maximum](https://en.wikipedia.org/wiki/Maximal_element) value of N measurements over the stated period."
    },
    {
      "code": "minimum",
      "display": "Minimum",
      "definition": "The [minimum](https://en.wikipedia.org/wiki/Minimal_element) value of N measurements over the stated period."
    },
    {
      "code": "count",
      "display": "Count",
      "definition": "The [number] of valid measurements over the stated period that contributed to the other statistical outputs."
    },
    {
      "code": "total-count",
      "display": "Total Count",
      "definition": "The total [number] of valid measurements over the stated period, including observations that were ignored because they did not contain valid result values."
    },
    {
      "code": "median",
      "display": "Median",
      "definition": "The [median](https://en.wikipedia.org/wiki/Median) of N measurements over the stated period."
    },
    {
      "code": "std-dev",
      "display": "Standard Deviation",
      "definition": "The [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) of N measurements over the stated period."
    },
    {
      "code": "sum",
      "display": "Sum",
      "definition": "The [sum](https://en.wikipedia.org/wiki/Summation) of N measurements over the stated period."
    },
    {
      "code": "variance",
      "display": "Variance",
      "definition": "The [variance](https://en.wikipedia.org/wiki/Variance) of N measurements over the stated period."
    },
    {
      "code": "20-percent",
      "display": "20th Percentile",
      "definition": "The 20th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period."
    },
    {
      "code": "80-percent",
      "display": "80th Percentile",
      "definition": "The 80th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period."
    },
    {
      "code": "4-lower",
      "display": "Lower Quartile",
      "definition": "The lower [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period."
    },
    {
      "code": "4-upper",
      "display": "Upper Quartile",
      "definition": "The upper [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period."
    },
    {
      "code": "4-dev",
      "display": "Quartile Deviation",
      "definition": "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."
    },
    {
      "code": "5-1",
      "display": "1st Quintile",
      "definition": "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."
    },
    {
      "code": "5-2",
      "display": "2nd Quintile",
      "definition": "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."
    },
    {
      "code": "5-3",
      "display": "3rd Quintile",
      "definition": "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."
    },
    {
      "code": "5-4",
      "display": "4th Quintile",
      "definition": "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."
    },
    {
      "code": "skew",
      "display": "Skew",
      "definition": "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)."
    },
    {
      "code": "kurtosis",
      "display": "Kurtosis",
      "definition": "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)."
    },
    {
      "code": "regression",
      "display": "Regression",
      "definition": "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."
    }
  ]
}