[Eeglablist] Filter causality pop_eegfiltnew

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Wed Jan 29 19:19:42 PST 2014


Dear Vito, Andreas, and Tim,

Let me revisit this topic.
Andreas, please correct me if I'm wrong.

The default EEGLAB filter (pop_eegfiltnew) outputs zero-phase lag results,
but is actually a *causal *and* linear-phase *filter. It shifts everything
back after the filtering by half the length of the filter. It means it does
not use filtfilt even though it is zero-phase lag. Vito, if my explanation
above is correct, EEGLAB filter should be fine for Granger analysis... Am I
correct?

Makoto


2014-01-16 Vito de Feo <vito.defeo at zmnh.uni-hamburg.de>

>  Dear Makoto,
>
> I attach you a couple of papers that illustrate the problems. To explain
> quickly the problem it is obvious that if you filter in both the directions
> (as an acausal filter does) you introduce a correlation beetwen the
> "future" and the "past".
>
> I need to filter the data to remove the 50 HZ (or 60 Hz if you are in USA
> or Japan) frequency. For the rest I don't filter.
>
> Best
>
>
> Vito
>
> Quoting Makoto Miyakoshi <mmiyakoshi at ucsd.edu>:
>
>  Dear Vito,
>
>  > the acausal filtering destroy the causality flow. For Granger it is
> important to use only causal filter.
>
>  Oh really. That sounds counterintuitive to me. Please send me the URL to
> the paper about it.
>
>  However let me tell you this that Tim Mullen (the author of SIFT) told us
> in the past EEGLAB workshop that we should not use ANY filter for SIFT. If
> you want to remove low-frequency drifts etc... he recommended the detrend
> option supported in SIFT. For low-pass filter, he said don't use it. Also
> make sure that you use double precision, not signle precision; check EEGLAB
> option to switch it (default should be single precision). Actually these
> were new things I learned!
>
>  Condro, for clarification to novice users, let me add this that EEGLAB's
> FIR filter is by default non-causal (i.e. peak latencies do not shift).
>
>  Makoto
>
> 2014/1/15 Vito de Feo <vito.defeo at zmnh.uni-hamburg.de>
>
>>
>>
>>
>>
>> *Dear Makoto, the acausal filtering destroy the causality flow. For
>> Granger it is important to use only causal filter. If you are interested I
>> can send you a paper about that. Yes, I know SIFT and I am also using it
>> for my analisys.*
>>
>>
>>
>>
>> *Vito Quoting Makoto Miyakoshi <mmiyakoshi at ucsd.edu
>> <mmiyakoshi at ucsd.edu>>:*
>>
>>
>>
>>  *Dear Andreas and Vito, *
>>
>>  *Sorry Andreas I screwed it when I typed your name.*
>>
>>  *Vito, I would like to learn from you the reason why you want to use
>> the minimum phase filter for Granger causality analysis. By the way, you
>> know SIFT is available for it? In case you don't know it yet, check
>> out http://sccn.ucsd.edu/wiki/SIFT <http://sccn.ucsd.edu/wiki/SIFT>.*
>>
>>  *Makoto*
>>
>>
>> *2014/1/14 Vito de Feo <vito.defeo at zmnh.uni-hamburg.de
>> <vito.defeo at zmnh.uni-hamburg.de>>*
>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> *Dear Andreas, I download the last version (13.1.1) and now the option
>>> is present and it is clearly written that the default is the zero-phase
>>> linear filtering. In my previous version (the last of the EEGLAB 12) this
>>> option was not present but now, with the version 13, it is present again!
>>> Best, Vito *
>>>
>>>
>>> *Quoting Andreas Widmann <widmann at uni-leipzig.de
>>> <widmann at uni-leipzig.de>>:*
>>>
>>> *Dear Vito,*
>>>>
>>>> *in the last eeglab version there is not the minphase parameter in the
>>>>> pop_eegfiltnew function.*
>>>>
>>>> *Which version is your last version? In 13.1.1 from the web page and in
>>>> rev 10261 from SVN the option is present. It was initially introduced in
>>>> EEGLAB 13 (but not backported to EEGLAB 12). Could you please check whether
>>>> possibly something went wrong with your setup/path and report back your
>>>> version number?*
>>>>
>>>> *It was useful to force the filter to be causal. If I have understand
>>>>> well now the filter is causal by dafault because it uses the filter
>>>>> funcion. Is this correct?*
>>>>
>>>>
>>>>
>>>>
>>>> *NO! Causal non-linear filter is NOT the default. Default is and will
>>>> remain zero-phase linear filtering. Default filter functions did not change
>>>> since EEGLAB 12. Best, Andreas*
>>>>
>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> *Sorry if this is a vey well known issue but I didn't find any answer
>>>>> on the web until now. I need filter causality for Granger analisys. If
>>>>> anyone has also other suggestion about causal filtering with eeglab, any
>>>>> suggestion is very welcome! Thank in advange! Vito -- Pflichtangaben gemäß
>>>>> Gesetz über elektronische Handelsregister und Genossenschaftsregister sowie
>>>>> das Unternehmensregister (EHUG): Universitätsklinikum Hamburg-Eppendorf
>>>>> Körperschaft des öffentlichen Rechts Gerichtsstand: Hamburg
>>>>> Vorstandsmitglieder: Prof. Dr. Christian Gerloff (Vertreter des
>>>>> Vorsitzenden) Prof. Dr. Dr. Uwe Koch-Gromus Joachim Prölß Rainer Schoppik
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>>>>> <eeglablist-request at sccn.ucsd.edu>-- Makoto Miyakoshi Swartz Center for
>>>>> Computational Neuroscience Institute for Neural Computation, University of
>>>>> California San Diego _______________________________________________
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>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> *-- Pflichtangaben gemäß Gesetz über elektronische Handelsregister und
>>> Genossenschaftsregister sowie das Unternehmensregister (EHUG):
>>> Universitätsklinikum Hamburg-Eppendorf Körperschaft des öffentlichen Rechts
>>> Gerichtsstand: Hamburg Vorstandsmitglieder: Prof. Dr. Christian Gerloff
>>> (Vertreter des Vorsitzenden) Prof. Dr. Dr. Uwe Koch-Gromus Joachim Prölß
>>> Rainer Schoppik*
>>>
>>
>>
>>
>> *-- *
>>
>>
>> *Makoto Miyakoshi Swartz Center for Computational Neuroscience Institute
>> for Neural Computation, University of California San Diego*
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *-- Pflichtangaben gemäß Gesetz über elektronische Handelsregister und
>> Genossenschaftsregister sowie das Unternehmensregister (EHUG):
>> Universitätsklinikum Hamburg-Eppendorf Körperschaft des öffentlichen Rechts
>> Gerichtsstand: Hamburg Vorstandsmitglieder: Prof. Dr. Christian Gerloff
>> (Vertreter des Vorsitzenden) Prof. Dr. Dr. Uwe Koch-Gromus Joachim Prölß
>> Rainer Schoppik*
>>
>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
>
>
>
>
> --
> Pflichtangaben gemäß Gesetz über elektronische Handelsregister und
> Genossenschaftsregister sowie das Unternehmensregister (EHUG):
>
> Universitätsklinikum Hamburg-Eppendorf
> Körperschaft des öffentlichen Rechts
> Gerichtsstand: Hamburg
>
> Vorstandsmitglieder:
> Prof. Dr. Christian Gerloff (Vertreter des Vorsitzenden)
> Prof. Dr. Dr. Uwe Koch-Gromus
> Joachim Prölß
> Rainer Schoppik
>



-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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