Dear Ngene Team,
can I please have your opinion on a couple of issues?
1) I am designing an experiment, for which I have 6 attributes (3^5 * 6*1). I have estimated some potential efficient designs in Ngene with 3 and 4 alternatives per choice sets, both with fixed priors and Bayesian priors. I can see that the for the attribute with 6 levels - price - I end up having some choice sets with the same level present in 2 alternatives, and, in some case, in all 3 alternatives. Could this lead to an overinflation of the importance of price when analysing the data? Almost as if respondents will take the price level as an unavoidable factor, so then they look into other attributes to determine their choice?
2) Is it necessary to have at least one attribute in a design with a different number of levels? In other words, can I design an efficient design if all attributes have, say, 3 levels or 4 levels, or, in that case, would it be better to design an orthogonal design?
Thanks,
Armando