# ZTest\_upper - script and chart function

ZTest\_upper() returns the aggregated value for the upper end of the confidence interval for two independent series of values.

This function applies to independent samples student's t-tests.

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\_upper (grp, value [, sig [, eq\_var]])

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.
* 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.
* sig: The two-tailed level of significance can be specified in sig. If omitted, sig is set to 0.025, resulting in a 95% confidence interval.
* 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.

Limitations:

Text values, NULL values and missing values in the expression value will result in the function returning NULL.

Examples:

`ZTest_upper( Group, Value )` `ZTest_upper( Group, Value, sig, false ) `

## Learn more

* [Examples of how to use z-test functions](https://help.qlik.com/en-US/qlikview/September2026/Subsystems/Client/Content/QV_QlikView/ChartFunctions/StatisticalTestFunctions/ztest/ztest-example.htm)