TTest_df() returns the aggregated student's t-test value (degrees of freedom) for two independent series of values.
This function applies to independent samples student's t-tests.
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.
TTest_df (grp, value [, eq_var])
Return data type: numeric
|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.|
|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.|
|eq_var||If eq_var is specified as False (0), separate variances of the two samples will be assumed. If eq_var is specified as True (1), equal variances between the samples will be assumed.|
Text values, NULL values and missing values in the expression value will result in the function returning NULL.
TTest_df( Group, Value )
TTest_df( Group, Value, false )