User Reference:P300Classifier

Synopsis

The P300 Classifier GUI (Graphical User Interface) is a tool that allows to train and test a linear classifier for detection of evoked related potentials collected with BCI2000. This GUI is designed for the analysis of BCI2000 data collected using the P3Speller or Stimuli Presentation paradigms. The program generates feature weights derived via the Stepwise Linear Regression technique. The specifics of the feature space and training routine can be manipulated using the GUI. The feature weights derived from the GUI can be saved and imported into BCI2000 as a parameter file fragment for online testing. The GUI provides the following functionality to investigators:

Classifier Training

Generates feature weights from BCI2000 P3Speller or Stimuli Presentation data files

Classifier Testing

Applies current feature weights to BCI2000 P3Speller or Stimuli Presentation data files and compares the results

Location

http://www.bci2000.org/svn/trunk/src/private/Tools/P300_classifier

Versioning

Author

Cristhian Potes

Source Code Revisions

• Initial development: --
• Tested under: --
• Known to compile under: --
• Broken since: --

Control Panel

The P300 Classifier GUI is composed of three panels: Data, Parameters, and Details.

Data Pane

Data Pane allows the user to:

• Load training and testing data files and an INI file.
• Generate and apply feature weights
• Write a parameter file fragment

Data pane

• [1] Load Training Data Files: Use this button to load BCI2000 data files for classifier training. The information for the selected files will appear at the top of the button.

• [2] Load Testing Data Files: Use this button to load BCI2000 data files for classifier testing. The information for the selected files will appear at the top of the button. Training and testing data files must be compatible.

• [3] Load Ini File: Use this button to load an INI file with all the parameters needed for the feature extraction.

• [4] Generate Feature Weights: Use this button to generate the feature weights after properly configuring all of the parameters in the Parameters pane. The suggested name for the parameter file fragment (*.prm) will appear at the top of the Write *.prm File button. This button will be enable only if the parameters are properly configured and there exists training data files.

• [5] Apply Feature Weights: Use this button to test the classification accuracy of the parameter file fragment currently stored in the GUI. The classification results will appear in the Details pane.

• [6] Write *.prm File: Use this button to save the parameters file fragment with the name suggested at the top of this button. The *.prm file is a BCI2000 parameter file fragment that can be imported into BCI2000 for online testing of the feature weights.

Parameters Pane

Parameters Pane contains all the parameters needed to generate the feature weights. These parameters can be loaded using the Load Ini File button. If the parameters are properly configured the Generate Feature Weights button is enabled.

Parameters pane

• [7] Max Model Features: Used to specify the maximum number of features to be kept in the SWLDA (Stepwise Linear Discriminant Analysis model). Only a single value can be entered for evaluation. The defaults is 60.

• [8] Penter: Used to specify the maximum p-value for a variable to be entered. The default is 0.1000. Penter must be less than Premove and 0<Penter<1. Only a single value can be entered for evaluation.

• [9] Premove: Used to specify the maximum p-value for a variable to be removed. The default is 0.1500. Premove must be greater than Penter and 0<Premove<1. Only a single value can be entered for evaluation.

• [10] Spatial Filter: Selects the spatial filter applied to the training data. Select RAW or CAR from the drop-down menu. RAW is no spatial filter applied to the data, and CAR is a common average reference filter using all of the channels contained in the data file (not just the channels specified in the GUI channel set). The default is RAW.

• [11] Decimation Frequency: Used to specify the temporal decimation frequency of the data in Hz. Only a single value can be entered for evaluation. Set this parameter to the Sampling Rate value for no decimation. The lower the Decimation Frequency, the less original data retained for processing.

• [12] Channel Set: Used to specify the channel set that will be used to create feature weights. The specified channels must be a subset of the channels contained in the training data file.

• [13] Response Window: Used to specify the Begin and End time points in milliseconds (ms) following the stimuli collected for the analysis. These two values are automatically converted into samples according to the sampling rate of the data (rounded). Only a single data window can be entered and will be evaluated. Begin must be less than End.

Details Pane

Details Pane displays information about the BCI2000 training data files and the classification results.