Variance

Returns the variance of a sample represented by a series of non-blank values in a field.

Format 

Variance ( field {; field...} )

Parameters 

field - any related field, repeating field, or set of non-repeating fields; or an expression that returns a field, repeating field, or set of non-repeating fields.

Parameters in braces { } are optional.

Data type returned 

number

Originated in version 

7.0

Description 

The variance of a distribution is a measure of how spread out the distribution is. Field can be any of the following:

  • a repeating field (repeatingField).
  • a field in matching related records specified by (table::field), whether or not these records appear in a portal.
  • several non-repeating fields in a record (field1;field2;field3...).
  • corresponding repetitions of repeating fields in a record (repeatingField1;repeatingField2;repeatingField3), if the result is returned in a repeating field with at least the same number of repeats.
  • several fields in the first matching record specified by (table::field1;table::field2;...). You can include fields from different tables (table 1::field A;table 2::field B...).

Equation

Example 1 

A portal displays the related values 5, 6, 7, and 8 in Scores.

Variance(table::Scores) returns 1.66666666....

Example 2 

In the following examples:

  • Field1 contains two repetitions with values of 1 and 2.
  • Field2 contains four repetitions with values of 5, 6, 7, and 8.
  • Field3 contains four repetitions with values of 6, 0, 4,and 4.
  • Field4 contains one repetition with a value of 3.

Variance(Field4) results in an error since the variance of a single value is not defined.

Variance(Field1;Field2;Field3) returns 7, 9.33333333..., 4.5, 8 if the calculation is a repeating field.

Example 3 

Two classes of students take an exam. Class 1 has scores of 70, 71, 70, 74, 75, 73, 72 and Class 2 has scores of 55, 80, 75, 40, 65, 50, 95. The variance for each class is:

Class 1: 3.80952380...

Class 2: 361.90476190...

The variance for Class 1 is much lower than the variance for Class 2, because the scores for Class 2 are more spread out.

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