# TTestw\_lower Script and chart function

TTestw\_lower() returns the aggregated value for the lower end of the confidence interval 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 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.

Syntax:

TTestw\_lower (weight, grp, value [, sig [, eq\_var]])

Return data type: numeric

Arguments:

Arguments

| Argument | Description |
| --- | --- |
| 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. |
| 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. |
| 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<br>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:

`TTestw_lower( Weight, Group, Value )` `TTestw_lower( Weight, Group, Value, sig, false )`

## Learn more

* [Creating a typical t-test report](https://help.qlik.com/en-US/cloud-services/Subsystems/Hub/Content/Sense_Hub/ChartFunctions/StatisticalTestFunctions/ttest/ttest_t_example.htm)