Discrete Choice Experiment - 3 two-level factors - Choice sets?

[SirAmVRo]

Hi Community.

I'm working on a discrete choice experiment with 3 factors with 2 levels each = 8 designs. I want to fully know the interaction between the factors and subject preference. I think a 28-set design of two alternatives each would be suitable: I want to confront the 8 designs to each other (8 C 2), like a football league of 8 teams everyone versus everyone. I'm new in SAS and I'm not sure how to develop this procedure. I'm following SAS Technical Support Documents--Marketing Research and I tried this code:

%mktruns(2 ** 3)

%mktex(2 ** 3, n=8)

proc print data=design(obs=8); run;

%choiceff(data=design,             /* candidate set of alternatives */

model=class(x1-x3 / sta),          /* model with stdzd orthogonal coding */

nsets=28,                          /* number of choice sets */

maxiter=8,                         /* maximum number of designs to make */

flags=2,                           /* 2 alternatives, generic candidates */

options=relative,                  /* display relative D-efficiency */

beta=zero)                         /* assumed beta vector, Ho: b=0 */

proc print; by set; id set; run;

%mktdups(generic, data=best, nalts=2, factors=x1-x3)

But I get duplicated sets. I want each factor to appear 7 times in the experiment. I would like to learn some suggestions from you.

Thank you very much in advance.

Ambrosio.