[Mne_analysis] temporal decoding: group analysis for mixed design

[JR KING]

While this paper raises an important subtlety (a significant t-test over
subjects' decoding accuracies indicates that there "are some people in the
population whose fMRI data carry information about the experimental
condition — but" [...] not that there is "an effect that is typical in the
population"), my understanding is that this particular issue is not a
problem for non-parametric statistics.

On 19 December 2017 at 11:15, Alday, Phillip <Phillip.Alday at mpi.nl> wrote:

> Do be careful when doing group-level statistics via inferential statistics
> on accuracy scores -- Allefeld at al 2016 show some of the problems with
> the naive approach using things like t-tests or ANOVA. You could use a
> Binomial/Bernoulli regression model to get around some of points they raise
> without needing to use their minimum information statistic.
>
> Best,
>
> Phillip
>
> On 18/12/17 11:24, JR KING wrote:
>
> Dear Yi-hui
>
> Decoding is generally not really adapted for mix-designed, as the models
> are traditionally fit at the single subject level - i.e. your model cannot
> be easily optimized to look for an across-subject effect.
>
> You can however compare the decoding scores across subjects/conditions as
> a first approximation, and specify individual subjects' score as your
> random variable.
>
> For multifactorial within-subject effects, a simple approach can be to
> implement RSA; we recently added this example in MNE:
> https://mne-tools.github.io/stable/auto_examples/decoding/
> decoding_rsa.html
>
> I will refer you to Kriegoskorte's RSA papers to see how you adapt this
> analysis to your specific needs,
>
> Kindest regards,
>
> Jean-Rémi
>
> On 18 December 2017 at 02:05, Yi-hui Hung <vedahung1116 at gmail.com> wrote:
>
>> Hello MNE experts,
>>
>> I have MEG data with two within-subject factors (each having 2 and 3
>> levels) and one between-subject factor (2 levels).  I performed decoding
>> analysis on my MEG data by using the function " time_decod.fit". The
>> question is how to perform group analysis in subject's decoding data in MNE
>> (or outside MNE) for my mixed design (2 x 3 x 2 factorial design). Besides,
>> I have another dependent variable by using "predict_proba" function to get
>> the predicting probability. I want to test whether the distribution of
>> predicting probability differ according to my design. Whether the
>> difference of the distribution continues in time (e.g., 200-300ms after
>> stimulus onset) does not matter. Suggestions will be appreciated.
>>
>>
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