Detrending
Detrending is used to remove the trend in the data by doing a line fit of
nuisance parameters with the data. The order of detrend is determined by the
nuisance parameters involved. GIFT uses four orders of detrend for removing the
trend from the ICA time course. The nuisance parameters (X) for each order are
shown below:
- Order 0
- X contains ones in first column.
-
- Order 1
- X includes ramp function with mean removed in first column and ones in
second column.
-
- Order 2
- X includes sine one cycle in first column, cosine one cycle in second
column, ramp function with mean removed in third column and ones in fourth
column.
-
- Order 3
- X includes sine two cycles in first column, cosine two cycles in second
column, sine one cycle in third column, cosine one cycle in fourth column, ramp
function with mean removed in fifth column and ones in sixth column.
Note: The row length equals the data in all the orders.