Contents:
Computes the standard deviation across column values of Integer or Decimal type using the sample statistical method.
The standard deviation of a set of values attempts to measure the spread in values around the mean and is used to measure confidence in statistical results. A standard deviation of zero means that all values are the same, and a small standard deviation means that the values are closely 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 population. More information is below.
This function is calculated across a sample of all values.
- For more information on a population version of this function, see STDEV Function.
If a row contains a missing or null value, it is not factored into the calculation. If no numeric values are detected in the input column, the function 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, see ROLLINGSTDEV Function.
Wrangle vs. SQL: This function is part of Wrangle, a proprietary data transformation language. Wrangle is not SQL. For more information, see Wrangle Language.
Basic Usage
stdevsamp(myRating)
Output: Returns the standard deviation of the values from the myRating column using the sample method of calculation.
Syntax and Arguments
stdevsamp(col_ref) [group:group_col_ref] [limit:limit_count]
| Argument | Required? | Data Type | Description |
|---|---|---|---|
| function_col_ref | Y | string | Name of column to which to apply the function |
For more information on the group and limit parameters, see Pivot Transform.
For more information on syntax standards, see Language Documentation Syntax Notes.
col_ref
Name of the column whose values you wish to use in the calculation. Column must be a numeric (Integer or Decimal) type.
- Literal values are not supported as inputs.
- Multiple columns and wildcards are not supported.
Usage Notes:
| Required? | Data Type | Example Value |
|---|---|---|
| Yes | String (column reference) | myValues |
Tip: For additional examples, see Common Tasks.
Examples
Functions: Source: Students took tests on three consecutive Saturdays: Transformation: You can use the following transformations to calculate standard deviation and variance across all dates using the sample method. Each computation has been rounded to three digits. You can use the following to limit the previous statistical computations to the last two Saturdays of testing: Results: Item Description
STDEVSAMP Function
Computes the standard deviation across column values of Integer or Decimal type using the sample statistical method.
VARSAMP Function
Computes the variance among all values in a column using the sample statistical method. Input column can be of Integer or Decimal. If no numeric values are detected in the input column, the function returns
0.
STDEVSAMPIF Function
Generates the standard deviation of values by group in a column that meet a specific condition using the sample statistical method.
VARSAMPIF Function
Generates the variance of values by group in a column that meet a specific condition using the sample statistical method.
ROUND Function
Rounds input value to the nearest integer. Input can be an Integer, a Decimal, a column reference, or an expression. Optional second argument can be used to specify the number of digits to which to round.
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 Name
New formula
Parameter: Formula type
Single row formula
Parameter: Formula
round(stdevsamp(Score), 3)
Parameter: New column name
'stdevSamp'
Transformation Name
New formula
Parameter: Formula type
Single row formula
Parameter: Formula
round(varsamp(Score), 3)
Parameter: New column name
'varSamp'
Transformation Name
New formula
Parameter: Formula type
Single row formula
Parameter: Formula
round(stdevsampif(Score, Date != '11\/9\/2019'), 3)
Parameter: New column name
'stdevSampIf'
Transformation Name
New formula
Parameter: Formula type
Single row formula
Parameter: Formula
round(varsampif(Score, Date != '11\/9\/2019'), 3)
Parameter: New column name
'varSampIf'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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