ZTest_dif() returns the aggregated z-test mean difference for a series of values.
If the function is used in the data 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.
Return data type: numeric
|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.|
Text values, NULL values and missing values in the expression value will result in the function returning NULL.