How to create trial variables

Trial variables represent the trials of a case document by a single value per trial. You use trial variables to report things like the path traveled per trial or the amount of time spent in a given quadrant etc. In the resulting scrollsheet, trial variables are represented as columns with one cell per trial. As you process the variable definitions, the Analyze Case Document command leaves you a choice of either analyzing all trials in a case document or only a selection of trials.

Two sequences of statements that you can use to define a trial variable are detailed below. Which one you choose depends on the type of information you want to be captured by the variable. If you you are mainly interested in temporal changes of a measure, the definition of the variable will involve a data matrix as intermediary result. If, however, you want to focus on the spatial distribution of a measure, calculation of the trial variable will also involve the creation of a data surface.

Capturing temporal changes using trial variables...

1. Create an active data matrix and selection mask using an appropriate combination of Matrix, Memory, Transform, Include and Exclude statements.
2. If you wish to limit the analysis to just a portion or time window of the trials, use the Window statement to set that window. If you omit the Window statement, all data points will be considered.
3. Use the Collapse statement to collapse the active 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. Execution of a Collapse statement does not destroy the active data matrix. You can use the statement repeatedly to create several data arrays from the same data matrix, e.g. containing maxima, minima, and averages of columns.
4. Use the Tabulate statement to create a trial variable based on a data array you have created. A trial variable reports the content of a data array as a column with one cell per array element (i.e. per trial). You can also use an expression referring to more than one data array as a source for a trial variable. In such an expression, the data arrays are combined element by element. You can use the Tabulate statement repeatedly to create more than one trial variable based on the same set of data arrays. Each Tabulate statement will add a new column to the resulting scrollsheet. At the beginning of the analysis, Wintrack will automatically create three columns listing the case name, case number and trial number for each row. These automatically created columns will prevent you from confounding the results from different cases if they are pooled in the same scrollsheet.
5. You may repeat steps 1 through 4 as many times as you wish, in order to create a set of trial variables that report data from different matrices.

Capturing spatial distribution using trial variables...

1. Create an active data matrix and selection mask using an appropriate combination of Matrix, Memory, Transform, Include and Exclude statements.
2. If you wish to limit the analysis to just a portion or time window of the trials, use the Window statement to set that window. If you omit the Window statement, all data points will be considered.
3. Use the Surface statement to represent the spatial distribution of data matrix values as a data surface. Its cells represent rectangular tiles which fill the surface of the arena. Data surfaces representing case documents with more than one trial have multiple trial planes, one for each trial in the case. Wintrack provides storage for 5 data surfaces, referred to as s1-s5. The Surface statement does not actually destroy the active data matrix. You can use it repeatedly to create several data surfaces from the same data matrix.
4. Apply the Collect statement to compute a data array representing a relevant aspect of the data surface with one value for each trial plane. Wintrack provides storage for 50 data arrays, referred to as a01-a10. You can apply the statement several times to compute different data values from the same data surface.
5. Use the Tabulate statement to create a trial variable based on a data array you have created. A trial variable reports the content of a data array as a column with one cell per array element (i.e. per trial). You can also use an expression referring to more than one data array as a source for a trial variable. In such an expression, the data arrays are combined element by element. You can use the Tabulate statement repeatedly to create more than one trial variable based on the same set of data arrays. Each Tabulate statement will add a new column to the resulting scrollsheet. At the beginning of the analysis, Wintrack will automatically create three columns listing the case name, case number and trial number for each row. These automatically created columns will prevent you from confounding the results from different cases if they are pooled in the same scrollsheet.
6. You may repeat steps 1 through 5 as many times as you wish, in order to create a set of trial variables that report data from different matrices.

Additional information...

• How to use conditional trial discarding explains how to discard trials based on analysis results.
• 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 Document command for basic information on that command.
• Inside case documents provides advanced information on case documents.