Using the T-Test By Groups Operator


The Spotfire Streaming T-Test By Groups operator is used to compute the two sample independent t-test where a two sample t-test is used to test the null hypothesis that the population means of two groups as measured on a single variable are significantly different from one another.

T-Test By Groups Properties

This section describes the properties you can set for this adapter, using the various tabs of the Properties view in StreamBase Studio.

General Tab

Name: Use this required field to specify or change the name of this instance of this component. The name must be unique within the current EventFlow module. The name can contain alphanumeric characters, underscores, and escaped special characters. Special characters can be escaped as described in Identifier Naming Rules. The first character must be alphabetic or an underscore.

Operator: A read-only field that shows the formal name of the operator.

Class name: Shows the fully qualified class name that implements the functionality of this adapter. If you need to reference this class name elsewhere in your application, you can right-click this field and select Copy from the context menu to place the full class name in the system clipboard.

Start options: This field provides a link to the Cluster Aware tab, where you configure the conditions under which this adapter starts.

Enable Error Output Port: Select this checkbox to add an Error Port to this component. In the EventFlow canvas, the Error Port shows as a red output port, always the last port for the component. See Using Error Ports to learn about Error Ports.

Description: Optionally, enter text to briefly describe the purpose and function of the component. In the EventFlow Editor canvas, you can see the description by pressing Ctrl while the component's tooltip is displayed.

Operator Properties Tab

Property Description
Equal Variance If enabled, the test will be performed assuming equal variances.
Log Level Controls the level of verbosity the adapter uses to send notifications to the console. This setting can be higher than the containing application's log level. If set lower, the system log level is used. Available values, in increasing order of verbosity, are: OFF, ERROR, WARN, INFO, DEBUG, TRACE.
Missing data deletion If casewise missing data deletion is selected, then all rows with missing data in at least one of the selected variables will be excluded from the analysis, otherwise if pairwise is selected, each correlation between a pair of variables will include all cases with valid data on both of those variables.

Field Select tab

Property Description
Response Specify the selected list of response variables. Regular expression matching is supported.
Group Specify the single categorical variable to be used as a grouping variable.

Codes for groups tab

Property Description
Code for group 1 Specify the code to be used to identify the first group
Code for group 2 Specify the code to be used to identify the second group

Cluster Aware Tab

Use the settings in this tab to enable this operator or adapter for runtime start and stop conditions in a multi-node cluster. During initial development of the fragment that contains this operator or adapter, and for maximum compatibility with releases before 10.5.0, leave the Cluster start policy control in its default setting, Start with module.

Cluster awareness is an advanced topic that requires an understanding of StreamBase Runtime architecture features, including clusters, quorums, availability zones, and partitions. See Cluster Awareness Tab Settings on the Using Cluster Awareness page for instructions on configuring this tab.

Concurrency Tab

Use the Concurrency tab to specify parallel regions for this instance of this component, or multiplicity options, or both. The Concurrency tab settings are described in Concurrency Options, and dispatch styles are described in Dispatch Styles.


Concurrency settings are not suitable for every application, and using these settings requires a thorough analysis of your application. For details, see Execution Order and Concurrency, which includes important guidelines for using the concurrency options.

Operator Ports

The operator expects that the response variables to be analyzed are of type 'double' and the single group variable is of type 'string'. The output tuple will consist of the incoming data passed through along with a list of the following analytic results for each response variable analyzed:

  1. Name of response variable

  2. Name of group variable

  3. Mean of group 1

  4. Mean of group 2

  5. Standard deviation of group 1

  6. Standard deviation of group 2

  7. N of group 1

  8. N of group 2

  9. Test statistic

  10. Degrees of freedom

  11. P-value