Dear Michiel

Thanks for your prompt and very helpful answer.

A couple of follow up questions

1) I tried to run my code below adding the *, but it comes up with this error.

A valid initial random design could not be generated after approximately 10 seconds. In this time, of the 206199 attempts made, there were 0 row repetitions, 363 alternative repetitions, and 205836 cases of dominance. There are a number of possible causes for this, including the specification of too many constraints, not having enough attributes or attribute levels for the number of rows required, and the use of too many scenario attributes. A design may yet be found, and the search will continue for 10 minutes. Alternatively, you can stop the run and alter the syntax.

The only variable that has an order is cost... all my other attributes are categorical. So, is adding the * not wise as technically there aren't any dominant alternatives (i.e. my non-cost attributes are not ordinal in nature... but I also want to get rid of repetitions which (please correct me if I am wrong), adding the * helps with identifying repetitions?

- Code: Select all
`Design`

; alts = A*, B*, C

; rows = 24

; eff = (mnl,d)

; block =2

; con

; model:

U(A) = b1[-0.0001]*Cost[500,1000,2000,0] +

b2.effects[0|0|0|0|0|0|0]*Loc[1,2,3,4,5,6,7,0] +

b3.effects[0|0]*Test[1,2,0] +

b4.effects[0|0|0]*Person[1,2,3,0] +

b5.effects[0]*Access[1,0]/

U(B) = b1*Cost +

b2.effects*Loc +

b3.effects*Test +

b4.effects*Person +

b5.effects*Access/

U(C) = b6[0]

$

2) If I want to analyze my data later using Latent Class Analysis as well as RPL, should I use the rppanel function for my experimental design instead of mnl? Is there an equivalent function for LCA or is MNL okay for this?

Thanks again for your help.

Best regards,

Jason Ong