Thanks for the comment.
But I've finished the tutorial(FT_analysis) and tried to work on the real data.
And the length of time series of the tutorial data and the data I've got from the subjects are different, so I think I should apply different polynomial order for 3dToutcount to the real dataset compared to the tutorial dataset, since the characteristics of the dataset are different.
That's why I ask how I can get the appropriate polynomial order for 3dToutcount. One of my seniors told me there would be an equation which helps me to calculate the polynomial order, but I couldn't find one.
I'd be very appreciated for your reply. Thanks.