In the PSPM Manual, the default filter that is used when setting up a GLM for SCR is defined as: unidirectional Butterworth band pass filter with cut off frequencies of 0.05 and 5 Hz, downsampling to 5 Hz. These optimal settings are apparently chosen based on the reference "A head-to-head comparison of scralyze and ledalab, two model-based methods for skin conductance analysis (Bach, 2014)". But as I understood it in this paper, the settings included a low pass filter with only a cut off frequency of 5Hz and data were down sampled to 10Hz. That's why I was wondering whether the filter definition as it is written in the Manual is the one that is used?
Many thanks,
Natalie
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Regarding the sample rate, there is a typo in the manual on page 26. Thanks for alerting us, we will correct this in the next release. Default sampling rate is 10 Hz, and if you go into the batch editor, you will see that indeed your data are downsampled at 10 Hz if you choose the default.
Default high pass filter is unidirectional at 0.05 Hz, as stated in the manual (p. 26) and also in the paper you cited (section 2.3, estimation of SA: "Data and design matrix were filtered with a unidirectional 1storder Butterworth high pass filter with cut off frequency of 0.05 Hz, according to current recommendations".
Note however that this recommendation is based on the paper "An improved algorithm for model-based analysis of evoked skin conductance responses" by Bach, Friston and Dolan, Biological Psychology 2013.
Hope this helps
Dominik
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Dear Dominik,
In the PSPM Manual, the default filter that is used when setting up a GLM for SCR is defined as: unidirectional Butterworth band pass filter with cut off frequencies of 0.05 and 5 Hz, downsampling to 5 Hz. These optimal settings are apparently chosen based on the reference "A head-to-head comparison of scralyze and ledalab, two model-based methods for skin conductance analysis (Bach, 2014)". But as I understood it in this paper, the settings included a low pass filter with only a cut off frequency of 5Hz and data were down sampled to 10Hz. That's why I was wondering whether the filter definition as it is written in the Manual is the one that is used?
Many thanks,
Natalie
Dear Natalie
thanks for the request.
Regarding the sample rate, there is a typo in the manual on page 26. Thanks for alerting us, we will correct this in the next release. Default sampling rate is 10 Hz, and if you go into the batch editor, you will see that indeed your data are downsampled at 10 Hz if you choose the default.
Default high pass filter is unidirectional at 0.05 Hz, as stated in the manual (p. 26) and also in the paper you cited (section 2.3, estimation of SA: "Data and design matrix were filtered with a unidirectional 1storder Butterworth high pass filter with cut off frequency of 0.05 Hz, according to current recommendations".
Note however that this recommendation is based on the paper "An improved algorithm for model-based analysis of evoked skin conductance responses" by Bach, Friston and Dolan, Biological Psychology 2013.
Hope this helps
Dominik