P300 Classifier GUI - Decimation Frequency

[micsfox]

The user reference recommends setting decimation frequency to Sampling Rate, however, in reality it can't be set above a 2 digit integer. What is the best way to set this parameter?

Does decimation effect the way that the linear classifier works? In other words, is there a setting for instructing the filter on how the epoch is divided into features? How does it interpret the features?

[gschalk]

Where does it state that one should set it to the sampling rate?

The decimation factor should be such that the resulting signal has a frequency of about 10-20 Hz. I.e., at 256 Hz sampling, the decimation factor can be around 20.

Gerv

[micsfox]

Thanks for your recommendation and your quick response.

Decimation frequency is mentioned here:
http://www.bci2000.org/wiki/index.php/U ... classifier
“Set this parameter to the Sampling Rate value for no decimation.”

[gschalk]

Hi,

I was wrong. Sorry. The decimation parameter is the target frequency, not the decimation factor. Thus, the default (20) is about right. Most of the P300 components are below 10 Hz, so we can downsample to 20 Hz without losing information.

Gerv