Computes the standard deviation across column values of Int= eger or Decimal type using the sample statistical method.

The **standard deviation** of a set of values attempts to m=
easure the spread in values around the mean and is used to measure confiden=
ce in statistical results. A standard deviation of zero means that all valu=
es are the same, and a small standard deviation means that the values are c=
losely bunched together. A high value for standard deviation indicates that=
the numbers are spread out widely. Standard deviation is always a positive=
value.

**NOTE: **This function applies to a sample of the entire p=
opulation. More information is below.

If a row contains a missing or null value, it is not factored into the c=
alculation. If no numeric values are detected in the input column, the func=
tion returns `0`

.

The square of standard deviation is variance. See VAR Function.

For a version of this function computed over a rolling window of rows, s= ee ROLLINGSTDEV Function.

**Wrangle vs. SQL:** This function is part of Wrangle , a proprietary data transformation language.=
Wrangle is not SQL. For more information, se=
e Wrangle Language.

stdevsamp(myRating)

**Output:** Returns the standard deviation=
of the values from the `myRating`

column using the sample metho=
d of calculation.

stdevsamp(col_ref) [group:group_col_ref] [= limit:limit_count]

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Argument | Required? | Data Type | Description |
---|---|---|---|

function_col_ref | Y | string | Name of column to which to apply the funct= ion |

For more information on the `group`

and `limit`

pa=
rameters, see Pivot Transform=
.

For more information on syntax standards, see Language Documentation Syntax Note= s.

Name of the column whose values you wish to use in the calculation. Colu= mn must be a numeric (Integer or Decimal) type.

- Literal values are not supported as inputs.
- Multiple columns and wildcards are not supported.

** Usage Notes: **

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Required? | Data Type | Example Value |
---|---|---|

Yes | String (column reference) | `myValues` |

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**Tip:** For additional examples, see Common Tasks.

This example shows some of the statistical functions that use the= sample method of computation. These include:

`STDEVSAMP`

- computes standard deviation using the sam= ple method. See STDEVSAMP= Function.`VARSAMP`

- computes variance using the sample met= hod. See VARSAMP Function.`STDEVSAMPIF`

- computes standard deviation based on a = condition and using the sample method. See STDEVSAMPIF Function.`VARSAMPIF`

- computes standard deviation based on= a condition and using the sample method. See VARSAMPIF Function.

**Source:**

Students took tests on three consecutive Saturdays:

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Student | Date | Score |
---|---|---|

Andrew | 11/9/19 | 81 |

Bella | 11/9/19 | 84 |

Christina | 11/9/19 | 79 |

David | 11/9/19 | 64 |

Ellen | 11/9/19 | 61 |

Fred | 11/9/19 | 63 |

Andrew | 11/16/19 | 73 |

Bella | 11/16/19 | 88 |

Christina | 11/16/19 | 78 |

David | 11/16/19 | 67 |

Ellen | 11/16/19 | 87 |

Fred | 11/16/19 | 90 |

Andrew | 11/23/19 | 76 |

Bella | 11/23/19 | 93 |

Christina | 11/23/19 | 81 |

David | 11/23/19 | 97 |

Ellen | 11/23/19 | 97 |

Fred | 11/23/19 | 91 |

**Transformation:**

You can use the following transformations to calculate standard deviatio= n and variance across all dates using the sample method. Each computation h= as been rounded to three digits.

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Transformation Name | <= code>New formula |
---|---|

Parameter: Formula type | `Single row formula` |

Parameter: Formula | `round(stdevsamp(Score), 3)` |

Parameter: New column name | `'stdevSamp'` |

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Transformation Name | <= code>New formula |
---|---|

Parameter: Formula type | `Single row formula` |

Parameter: Formula | `round(varsamp(Score), 3)` |

Parameter: New column name | `'varSamp'` |

You can use the following to limit the previous statistical computations= to the last two Saturdays of testing:

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Transformation Name | <= code>New formula |
---|---|

Parameter: Formula type | `Single row formula` |

Parameter: Formula | ```
round(stdevsampif(Score, Date !=3D '11\/9\=
/2019'), 3)
``` |

Parameter: New column name | `'stdevSampIf'` |

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Transformation Name | <= code>New formula |
---|---|

Parameter: Formula type | `Single row formula` |

Parameter: Formula | ```
round(varsampif(Score, Date !=3D '11\/9\/2=
019'), 3)
``` |

Parameter: New column name | `'varSampIf'` |

**Results:**

Student | Date | Score | varSampIf | stdevSampIf | varSamp | stdevSamp |
---|---|---|---|---|---|---|

Andrew | 11/9/19 | 81 | 94.515 | 9.722 | 131.673 | 11.475 |

Bella | 11/9/19 | 84 | 94.515 | 9.722 | 131.673 | 11.475 |

Christina | 11/9/19 | 79 | 94.515 | 9.722 | 131.673 | 11.475 |

David | 11/9/19 | 64 | 94.515 | 9.722 | 131.673 | 11.475 |

Ellen | 11/9/19 | 61 | 94.515 | 9.722 | 131.673 | 11.475 |

Fred | 11/9/19 | 63 | 94.515 | 9.722 | 131.673 | 11.475 |

Andrew | 11/16/19 | 73 | 94.515 | 9.722 | 131.673 | 11.475 |

Bella | 11/16/19 | 88 | 94.515 | 9.722 | 131.673 | 11.475 |

Christina | 11/16/19 | 78 | 94.515 | 9.722 | 131.673 | 11.475 |

David | 11/16/19 | 67 | 94.515 | 9.722 | 131.673 | 11.475 |

Ellen | 11/16/19 | 87 | 94.515 | 9.722 | 131.673 | 11.475 |

Fred | 11/16/19 | 90 | 94.515 | 9.722 | 131.673 | 11.475 |

Andrew | 11/23/19 | 76 | 94.515 | 9.722 | 131.673 | 11.475 |

Bella | 11/23/19 | 93 | 94.515 | 9.722 | 131.673 | 11.475 |

Christina | 11/23/19 | 81 | 94.515 | 9.722 | 131.673 | 11.475 |

David | 11/23/19 | 97 | 94.515 | 9.722 | 131.673 | 11.475 |

Ellen | 11/23/19 | 97 | 94.515 | 9.722 | 131.673 | 11.475 |

Fred | 11/23/19 | 91 | 94.515 | 9.722 | 131.673 | 11.475 |

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