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The files will be ordered alphabetically; knowing the order is required for the later steps (specifically, creating the design matrix).
Design
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matrix
Note: Create this file using the FSL "Glm" GUI, as other important files are created at the same time.
Click to example of two-group, 96 subject design matrix file.
The design matrix is a text file with header information and numbers in columns. by traditionalBy tradition, the file is saved with a name like "design.mat" but you could also use "design.txt." " (so it opens in Notepad, since *.mat files may open in MATLAB). Each row represents a subject, in the order stored in the concatenated bvars file. The simplest design matrix (for a two group dataset) is a two columns, with the first +1 for rows in group 1 and 0 otherwise, and similarly +1 in the second column for rows in the second group. There is also header information which includes the number of columns (I think), the number of subjects, and the maximum value of each column. For example, here is a two-group, 5 subjects/group design matrix:
Create this file and save it in the same directory as everything else. You can also set up this design matrix using FSL. Type "cd" to the directory, and type Glm (case sensitive), select "Higher-level / non-timeseries design" from the pull-down menu, enter the number of subjects (# inputs), click Wizard, select "two groups, unpaired", enter the number of subjects in group 1, click Process, then Save. When saving, navigate to something like \mnt\hgfs\LinuxShare\temp, and choose a file name like design_2group.mat."
In addition to design.mat (or whatever name you saved it as), you will see design.con, design.fsf, and other files.