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Dear Michiel,

Thanks so much for taking the time to answer these questions - of course, your expert advice worked great and I was able to generate my final Bayesian efficient design!

Best,

Rob

*EDIT*

Apologies for an extra question.

In the above post I mentioned that I can't see anything immediately wrong with the choice tasks the ngene code below creates.

I realise I use quite a few restrictions so as to not present dominant alternatives and also keep attributes constant (LIFE, QOL ...

Dear Michiel,

Thanks for you prompt reply.

As you suggested, I removed some interactions that I had in my original ngene model specification and ran the model (in Apollo) to obtain priors. Below is the output:


Estimates:
Estimate s.e. t.rat.(0) p(1-sided) Rob.s.e. Rob.t.rat.(0) p(1-sided)
asc ...

Dear Michiel,

When generating an efficient design, I understand that the process looks roughly something like: starting position e.g., a D-Efficient design, conduct pilot in ~10% of your sample using this design, run the model (e.g., an MNL model in Apollo) using the same model spec as specified in ...

Thanks, Michiel for your quick reply.

Dear Michiel,

For the purposes of obtaining priors, I have a question relating to the code above, specifically when it comes to the interaction of a categorical scenario variable, with another categorical variable.

In this ngene example, [CERT] is coded as a categorical dummy variable with 4 ...

Thanks Michiel - much appreciated!

Dear Michiel,

Thank you for your useful advice. Using this trick works and I am much nearer to finalising my experimental design. However I have a few additional questions on including scenario variables that I am unable to answer from your slides or the ngene user manual that I hope you can shed ...

Dear Michiel,

I have a quick question on adding a dummy coded, scenario variable into my design without first including it as a main effect in the utility function in ngene. I can't find the answer in the manual, in this forum or in your slides.

Brief background
My experiment requires ...