Statistics Debug Scenario
Posted: Tue Jul 11, 2017 11:22 pm
Hi,
I made a debug scenario to compare different (cumulative / real-time) Descriptive Statistics (Mean, Variance,...) Calculation Methods in openvibe and to crossvalidate the results with other programs (SPSS and EEGLab). Mainly I wanted to compare the DSP Raw Signal Results with the FFT Results.
The reference statistic results were calculated with SPSS - the EEGLab Channel Statistics seem to match the SPSS results exactly.
Scenario Screenshots
Statistics
better resolution http://i.imgur.com/rmm6RRo.png
Statistics Result Displays
SPSS Descriptive Statistics Output
C3 = Raw Data
C3centered = Raw Data (Baseline / DC-Offset removed)
* C3absolute = Magnitude / Amplitude
C3power = Magnitude²
Reference Data:
The reference data is the default ${Path_Samples}/signals/bci-motor-imagery.ov file, so no additional data needed
to be downloaded.
(However this set turned out to be not the best suited dataset, due to a signal offset and zeroes at the end of the file)
Simple Preprocessing was necessary:
http://i.imgur.com/cL6Gsr2.png
original and transformed Signal Data Histogram (just for fun)
http://i.imgur.com/XVcLB8X.png
Scenario File
My conclusions in short:
*I could not get comparable results of the Signal Amplitude calculation and the FFT Amplitude calculation.
(Here I assume a mistake in the FFT calculation chain)
*The Univariate Statistics Box did not show useful results besides of the mean
(wrong usage)?
*Overall Epoch Variance Box statistics calculation seems to be the most robust method and
showed very similar results in comparison to the SPSS output
Now it would be great to be able to capture the final (cumulated) calculation step to export as a single row or case.
If you have any suggestions, feel free to share it. Hints to bugs and errors are also very appreciated
Best,
Lee
I made a debug scenario to compare different (cumulative / real-time) Descriptive Statistics (Mean, Variance,...) Calculation Methods in openvibe and to crossvalidate the results with other programs (SPSS and EEGLab). Mainly I wanted to compare the DSP Raw Signal Results with the FFT Results.
The reference statistic results were calculated with SPSS - the EEGLab Channel Statistics seem to match the SPSS results exactly.
Scenario Screenshots
Statistics
better resolution http://i.imgur.com/rmm6RRo.png
Statistics Result Displays
SPSS Descriptive Statistics Output
C3 = Raw Data
C3centered = Raw Data (Baseline / DC-Offset removed)
* C3absolute = Magnitude / Amplitude
C3power = Magnitude²
Reference Data:
The reference data is the default ${Path_Samples}/signals/bci-motor-imagery.ov file, so no additional data needed
to be downloaded.
(However this set turned out to be not the best suited dataset, due to a signal offset and zeroes at the end of the file)
Simple Preprocessing was necessary:
http://i.imgur.com/cL6Gsr2.png
original and transformed Signal Data Histogram (just for fun)
http://i.imgur.com/XVcLB8X.png
Scenario File
My conclusions in short:
*I could not get comparable results of the Signal Amplitude calculation and the FFT Amplitude calculation.
(Here I assume a mistake in the FFT calculation chain)
*The Univariate Statistics Box did not show useful results besides of the mean
(wrong usage)?
*Overall Epoch Variance Box statistics calculation seems to be the most robust method and
showed very similar results in comparison to the SPSS output
Now it would be great to be able to capture the final (cumulated) calculation step to export as a single row or case.
If you have any suggestions, feel free to share it. Hints to bugs and errors are also very appreciated
Best,
Lee