For each discrete (categorical) factor, there could exist a file named <factor>.levels which lists all possible levels. These are not necessary to run qdec, but can be used to control the order different factors are displayed. For example, accompanying the example qdec.table.dat file:
fsid gender age Left-Hippocampus Right-Hippocampus 140 Female 18 4214 4190 049 Male 19 4543 4153 141 Female 20 3896 3741 084 Male 21 4804 4722 021 Male 22 4021 3969 093 Female 22 3603 3597
there could be an accompanying file named gender.levels containing these lines NOTE: make sure that the file ends with a new line:
If many categorical factors are used, .levels files can be created for each one. For example, if your qdec table also included a column called diagnosis with 3 levels (Control, AD, and MCI), a file called diagnosis.levels can be included, with these lines:
Control AD MCI
The <factor>.levels files should be included in the same directory as the qdec table file. Usual a qdec subdirectory is created inside the SUBJECTS_DIR to save these files, as well as the output of qdec analysis.