Experimental design is Tab-separated values file. This file has two columns, the first one corresponds to the sample name and the second one corresponds to the phenotype.

sample1	Group_1
sample2	Group_1
sample3	Group_2

Note: In case of paired data the Experimental design file must be ordered.

Here is an example of a file with 4 piared samples (sample1_Normal and sample1_Treated are the same sample before and after treatment):

sample1_Normal	Group_1
sample2_Normal	Group_1
sample1_Treated	Group_2
sample2_Treated	Group_2

Here is an other file example see brca_normal-basal_ed.txt.