* One way to list all 2^n combinations and identify treatment combinations satisfying the defining relation for a fractional factorial design. This is the example from the text in section 12.5 ; data fracfact ; do a = -1 to 1 by 2 ; do b = -1 to 1 by 2 ; do c = -1 to 1 by 2 ; do d = -1 to 1 by 2 ; do e = -1 to 1 by 2 ; do f = -1 to 1 by 2 ; abde = a*b*d*e ; abcf = a*b*c*f ; output ; end ; end ; end ; end ; end ; end ; run ; proc sort data = fracfact ; by abde abcf ; proc print data = fracfact ; var a b c d e f abde abcf ; run ; proc print data = fracfact (where = (abde + abcf = 2)) ; var a b c d e f abde abcf ; run ; data fracfact2 ; set fracfact ; la = ' ' ; lb = ' ' ; lc = ' ' ; ld = ' ' ; le = ' ' ; lf = ' ' ; if a = 1 then la = 'a' ; if b = 1 then lb = 'b' ; if c = 1 then lc = 'c' ; if d = 1 then ld = 'd' ; if e = 1 then le = 'e' ; if f = 1 then lf = 'f' ; combo = cats(la,lb,lc,ld,le,lf) ; run ; proc print data = fracfact2 (where = (abde + abcf = 2)) ; var a b c d e f combo abde abcf ; run ;