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ZTest

Calculate a z-test.

This node support 1-sample and 2-sample unpaired and paired z-tests. The node requires that the data has an instance axis. In order to use 2-sample z-tests, the instance axis must have a field (e.g., 'Marker' or 'TargetValue') according to which the individual trials can be grouped. The node performs multiple mass-univariate z-tests when additional axes are present in the data. In the output packet, the instance axis will be replaced by a statistic axis (with label 'statistic_types'), which has fields for the z-value and the p-value. A feature axis is also added (with label 'explanatory_variables'), with a single element specifying the comparison pair. (Note: For backward compatibility reasons (versions < 0.9.0), legacy_mode is set to True and therefore this node will store the stats in a Feature axis instead of a Statistic axis. Please update your pipelines as needed to assume a Statistic axis and then set legacy_mode to False. This will be deprecated in a future release.) Version 0.9.0

Ports/Properties

data

A packet containing at least one signal chunk with an instance axis. For two-sample z-tests, the instances must be separated into two groups according to an instance axis data field. For paired z-tests, these two groups must be identical in size and have another instance axis data field to indicate sample pairing.

  • verbose name: Data
  • default value: None
  • port type: DataPort
  • value type: Packet (can be None)
  • data direction: INOUT

comparison_value

In the one sample case, value is the mean under the Null hypothesis. In the two sample case, value is the difference between means under the Null hypothesis. The test statistic is x1_mean - x2_mean - value.

  • verbose name: Comparison Value
  • default value: 0
  • port type: FloatPort
  • value type: float (can be None)

trim_proportion

Proportion of data instances to trim (per variable) on the lower and upper tails of the data. If only a single number is provided then it is used for both lower and upper. If no non-zero numbers are provided then no trimming is performed (default).

  • verbose name: Trim Proportion
  • default value: [0, 0]
  • port type: ListPort
  • value type: list (can be None)

winsorize

If trim_proportion has a non-zero value, then setting winsorize to True (default) will cause winsorization to be used instead of standard trimming.

  • verbose name: Winsorize
  • default value: True
  • port type: BoolPort
  • value type: bool (can be None)

legacy_mode

Store the statistics in a Feature axis instead of a Statistic axis. Included for backward compatibility, and will be deprecated.

  • verbose name: Legacy Mode
  • default value: True
  • port type: BoolPort
  • value type: bool (can be None)

use_caching

Enable caching.

  • verbose name: Use Caching
  • default value: False
  • port type: BoolPort
  • value type: bool (can be None)

set_breakpoint

Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.

  • verbose name: Set Breakpoint (Debug Only)
  • default value: False
  • port type: BoolPort
  • value type: bool (can be None)

metadata

User-definable meta-data associated with the node. Usually reserved for technical purposes.

  • verbose name: Metadata
  • default value: {}
  • port type: DictPort
  • value type: dict (can be None)