[FieldTrip] Phase Lag Index

[jan-mathijs schoffelen]

Hi Lidia,

Transforming a number that is bounded between -1 and 1 into a number that has absolute value and is bounded between 0 and 1 can be achieved by taking the abs().
Alternatively, you could compute the classic PLI from a time series of complex-valued cross-spectral density estimates by abs(mean(sign(angle(x))));

Best,
Jan-Mathijs


On Jun 24, 2014, at 12:46 AM, Lidia Mijas <lid.mijas at gmail.com> wrote:

> Hi everyone,
> 
> I would like to compute a classic phase lag index between pairs of MEG time series. 
> 
> So far I only found a wieghted phase lag index method implemented in ft and as far as I understand it is a directed measure so it gives the values from -1 to 1. Has anyone have an idea how to transform it so it computes  absolute values from 0 to 1???
> 
> Many thanks in advance.
> 
> Regards,
> Lidia
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Jan-Mathijs Schoffelen, MD PhD 

Donders Institute for Brain, Cognition and Behaviour, 
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands

Max Planck Institute for Psycholinguistics,
Nijmegen, The Netherlands

J.Schoffelen at donders.ru.nl
Telephone: +31-24-3614793

http://www.hettaligebrein.nl

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