ZTestw_dif - script and chart function

ZTestw_dif() returns the aggregated z-test mean difference for a series of values.

This function applies to z-tests where the input data series is given in weighted two-column format.

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:  

ZTestw_dif ( weight, value [, sigma]) 

Return data type: numeric

Arguments:  

Argument Description
value The values should be returned by value. A sample mean of 0 is assumed. If you want the test to be performed around another mean, subtract that value from the sample values.
weight Each sample value in value can be counted one or more times according to a corresponding weight value in weight.
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:  

ZTestw_dif( Weight, Value-TestValue)

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