How to use conditional trial discarding
When processing variable definitions, the Analyze Case Document command leaves you the choice of either analyzing all trials in a case document or only a selection of trials. In addition, conditional trial discarding allows to evaluate a particular parameter for each trial in a case document and to keep or discard trials depending on the result. This works for all types of variables. For example you could discard all trials in which the path traveled is less than a given minimal length. Once a trial has been discarded during processing of a variable definition file, it will be ignored by all data matrices that are created thereafter. This is how you proceed for conditional trial deletion:
- Create an active data matrix and selection mask using an appropriate combination of Matrix, Transform, Include and Exclude statements.
- Use the Collapse statement to collapse the data matrix into a data array. Each element of a data array stands for one column of the data matrix, that is for one trial. Wintrack provides storage for 50 data arrays, referred to as a01-a50. The Collapse statement does not actually destroy the active data matrix. You can use it repeatedly to create several data arrays from the same data matrix, e.g. containing maxima, minima, and averages of columns.
- Use the Discard statement to discard trials depending on the values of the elements in the data array. You may use it repeatedly to apply a whole set of conditions.
- Discarded trials will be treated as missing trials and thus completely ignored in any subsequently created data matrix.
Additional information...
- Managing custom variable definition files provides general information on the management of custom variable definition files.
- There is a topic describing how to build a custom variable definition file.
- The Flowchart of advanced data analysis gives a synopsis of data and variable types.
- There is a list of all available variable definition statements.
- Using the Memory statement you can build collections of data matrices and selection masks for later reuse in other variables.
- See Analyze Case command for basic information on that command.
- Inside case documents provides advanced information on case documents.
