**Table of Contents****Artifacts Summary****StatisticsCode**

This page is part of the HL7 Terminology (v4.0.0: Release) based on FHIR R4. The current version which supercedes this version is 5.2.0. For a full list of available versions, see the Directory of published versions

Draft as of 2020-04-09 |

```
{
"resourceType" : "CodeSystem",
"id" : "observation-statistics",
"meta" : {
"lastUpdated" : "2020-04-09T21:10:28.568+00:00"
},
"text" : {
"status" : "generated",
"div" : "<div xmlns=\"http://www.w3.org/1999/xhtml\"><p>This code system <code>http://terminology.hl7.org/CodeSystem/observation-statistics</code> defines the following codes:</p><table class=\"codes\"><tr><td style=\"white-space:nowrap\"><b>Code</b></td><td><b>Display</b></td><td><b>Definition</b></td></tr><tr><td style=\"white-space:nowrap\">average<a name=\"observation-statistics-average\"> </a></td><td>Average</td><td>The [mean](https://en.wikipedia.org/wiki/Arithmetic_mean) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">maximum<a name=\"observation-statistics-maximum\"> </a></td><td>Maximum</td><td>The [maximum](https://en.wikipedia.org/wiki/Maximal_element) value of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">minimum<a name=\"observation-statistics-minimum\"> </a></td><td>Minimum</td><td>The [minimum](https://en.wikipedia.org/wiki/Minimal_element) value of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">count<a name=\"observation-statistics-count\"> </a></td><td>Count</td><td>The [number] of valid measurements over the stated period that contributed to the other statistical outputs.</td></tr><tr><td style=\"white-space:nowrap\">total-count<a name=\"observation-statistics-total-count\"> </a></td><td>Total Count</td><td>The total [number] of valid measurements over the stated period, including observations that were ignored because they did not contain valid result values.</td></tr><tr><td style=\"white-space:nowrap\">median<a name=\"observation-statistics-median\"> </a></td><td>Median</td><td>The [median](https://en.wikipedia.org/wiki/Median) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">std-dev<a name=\"observation-statistics-std-dev\"> </a></td><td>Standard Deviation</td><td>The [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">sum<a name=\"observation-statistics-sum\"> </a></td><td>Sum</td><td>The [sum](https://en.wikipedia.org/wiki/Summation) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">variance<a name=\"observation-statistics-variance\"> </a></td><td>Variance</td><td>The [variance](https://en.wikipedia.org/wiki/Variance) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">20-percent<a name=\"observation-statistics-20-percent\"> </a></td><td>20th Percentile</td><td>The 20th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">80-percent<a name=\"observation-statistics-80-percent\"> </a></td><td>80th Percentile</td><td>The 80th [Percentile](https://en.wikipedia.org/wiki/Percentile) of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">4-lower<a name=\"observation-statistics-4-lower\"> </a></td><td>Lower Quartile</td><td>The lower [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">4-upper<a name=\"observation-statistics-4-upper\"> </a></td><td>Upper Quartile</td><td>The upper [Quartile](https://en.wikipedia.org/wiki/Quartile) Boundary of N measurements over the stated period.</td></tr><tr><td style=\"white-space:nowrap\">4-dev<a name=\"observation-statistics-4-dev\"> </a></td><td>Quartile Deviation</td><td>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.</td></tr><tr><td style=\"white-space:nowrap\">5-1<a name=\"observation-statistics-5-1\"> </a></td><td>1st Quintile</td><td>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.</td></tr><tr><td style=\"white-space:nowrap\">5-2<a name=\"observation-statistics-5-2\"> </a></td><td>2nd Quintile</td><td>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.</td></tr><tr><td style=\"white-space:nowrap\">5-3<a name=\"observation-statistics-5-3\"> </a></td><td>3rd Quintile</td><td>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.</td></tr><tr><td style=\"white-space:nowrap\">5-4<a name=\"observation-statistics-5-4\"> </a></td><td>4th Quintile</td><td>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.</td></tr><tr><td style=\"white-space:nowrap\">skew<a name=\"observation-statistics-skew\"> </a></td><td>Skew</td><td>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).</td></tr><tr><td style=\"white-space:nowrap\">kurtosis<a name=\"observation-statistics-kurtosis\"> </a></td><td>Kurtosis</td><td>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).</td></tr><tr><td style=\"white-space:nowrap\">regression<a name=\"observation-statistics-regression\"> </a></td><td>Regression</td><td>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.</td></tr></table></div>"
},
"url" : "http://terminology.hl7.org/CodeSystem/observation-statistics",
"identifier" : [
{
"system" : "urn:ietf:rfc:3986",
"value" : "urn:oid:2.16.840.1.113883.4.642.1.1126"
}
],
"version" : "0.1.0",
"name" : "StatisticsCode",
"title" : "StatisticsCode",
"status" : "draft",
"experimental" : false,
"date" : "2020-04-09T21:10:28+00:00",
"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://terminology.hl7.org/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."
}
]
}
```

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