ZTest_dif() returns the aggregated z-test mean difference for a series of values.
If the function is used in the load script, the values are iterated over a number of records as defined by a group by clause.
If the function is used in a chart expression, the values are iterated over the chart dimensions.
Syntax:
ZTest_dif(value[, sigma])
Return data type: numeric
Arguments:
- value: The sample values to be evaluated. A population mean of 0 is assumed. If you want the test to be performed around another mean, subtract that mean from the sample values.
- sigma: If known, the standard deviation can be stated in sigma. If sigma is omitted the actual sample standard deviation will be used.
Limitations:
Text values, NULL values and missing values in the expression value will result in the function returning NULL.
Example:
ZTest_dif(Value-TestValue)
