SKEW Function | Teradata Vantage - 17.10 - SKEW - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Functions, Expressions, and Predicates

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1145-171K
Language
English (United States)

Returns the skewness of the distribution of value_expression.

This function returns the REAL data type.

To invoke the time series version of this function, use the GROUP BY TIME clause. For more information, see Teradata Vantage™ - Time Series Tables and Operations, B035-1208.

Skewness

Skewness is the third moment of a distribution. It is a measure of the asymmetry of the distribution about its mean compared with the normal, Gaussian, distribution.

The normal distribution has a skewness of 0.

Positive skewness indicates a distribution having an asymmetric tail extending toward more positive values, while negative skewness indicates an asymmetric tail extending toward more negative values.

Computation

The equation for computing SKEW is defined as follows:



where:

This variable … Represents …
x value_expression

Conditions That Produce a Null Result

The following conditions product a null result:
  • Fewer than three non-null data points in the data used for the computation
  • STDDEV_SAMP(x) = 0
  • Division by zero