TTestw_dif() returns the aggregated student's t-test mean difference for two independent series of values.
This function applies to two independent samples student's t-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:
TTestw_dif (weight, group, value)
Return data type: numeric
Arguments:
- value: The sample values to be evaluated. The sample values must be logically grouped as specified by exactly two values in group. If a field name for the sample values is not provided in the load script, the field will automatically be named Value.
- weight: Each value in value can be counted one or more times according to a corresponding weight value in weight.
- grp: The field containing the names of each of the two sample groups. If a field name for the group is not provided in the load script, the field will automatically be given the name Type.
Limitations:
Text values, NULL values and missing values in the expression value will result in the function returning NULL.
Examples:
TTestw_dif( Weight, Group, Value )
TTestw_dif( Weight, Group, Value, false )
