Hello All, I am using Warren Kuhfeld's excellent macros to do a conjoint design using choice experiments. I have 4 3 level factors. I want to estimate main effects and selected interactions. I will use 2 generic alternatives, and a "none" option which is fixed at 1,1,1,1 for the four levels. The problem i am facing is that the design i find seems odd. In every choice set, the levels of first factor X1 are identical for Alternatives 1 &2 in every choice set. This should not be happening, as they should be changing too. Any insights will be appreciated. Here is some code and output. Thanks Manoj Agarwal /* Rider Model Price 3 Wait time 3 Driver quality 3 Car quality 3*/ %mktruns(3 3 3 3,interact=x1*X2 x1*x3 x1*x4 ); /* will use the full factorial of 81 */ %mktex( 3 3 3 3,n=81,seed=100); /* 3 options showed set the constant alternative it sets to 1 1 1 1 )*/ data final(drop=i); set design end=eof; retain f1-f2 1 f3 0; output; if eof then do; array x[7] x1-x4 f1-f3; do i=1 to 7;x[i] = i le 4 or i eq 7; end; output; end; run; /* after some experimentation, decided to use 18 choice sets for the interaction design*/ %choiceff(data=final, model=class(x1-x4)class(x1*x2 x1*x3 x1*x4/sta), nsets=18,seed=125,maxiter=100,flags=f1-f3,options=relative nodups,beta=zero); Block Set Alt x1 x2 x3 x4 1 1 1 1 1 3 3 1 1 2 1 3 1 2 1 1 3 1 1 1 1 1 2 1 1 3 2 1 1 2 2 1 2 1 3 1 2 3 1 1 1 1 1 3 1 2 1 3 1 1 3 2 2 3 2 2 1 3 3 1 1 1 1 1 4 1 3 2 1 2 1 4 2 3 1 2 1 1 4 3 1 1 1 1 1 5 1 3 2 2 3 1 5 2 3 3 3 1 1 5 3 1 1 1 1 1 6 1 1 2 2 3 1 6 2 1 1 3 2 1 6 3 1 1 1 1 1 7 1 2 1 2 2 1 7 2 2 3 3 1 1 7 3 1 1 1 1 1 8 1 2 2 3 2 1 8 2 2 3 1 3 1 8 3 1 1 1 1 1 9 1 3 2 2 1 1 9 2 3 1 1 3 1 9 3 1 1 1 1 2 1 1 1 2 3 1 2 1 2 1 1 2 3 2 1 3 1 1 1 1 2 2 1 2 2 1 3 2 2 2 2 3 2 1 2 2 3 1 1 1 1 2 3 1 2 1 2 1 2 3 2 2 3 3 2 2 3 3 1 1 1 1 2 4 1 1 2 2 2 2 4 2 1 3 3 3 2 4 3 1 1 1 1 2 5 1 3 1 3 2 2 5 2 3 3 1 1 2 5 3 1 1 1 1 2 6 1 3 3 3 3 2 6 2 3 1 1 1 2 6 3 1 1 1 1 2 7 1 2 1 3 3 2 7 2 2 2 1 1 2 7 3 1 1 1 1 2 8 1 2 2 2 3 2 8 2 2 1 1 2 2 8 3 1 1 1 1 2 9 1 3 2 3 1 2 9 2 3 3 2 2 2 9 3 1 1 1 1
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