Simulation with Conjoint Analysis

Hi everyone,

With SPSS when I run a simulation with conjoint analysis I got this message:

"142 out of 155 subjects are used in the Bradley-Terry-Luce and Logit methods because these subjects have all nonnegative scores".

I think SPSS excluded those respondents because their simulated score was negative for some profiles.

Each excluded respondent displays this message:
"Negative simulation scores or all zero simulation scores are found. This subject will not be included in computing preference probabilities using the Bradley-Terry-Luce or Logit methods"

Is there a way to include the excluded subject?
Is it possible to avoid this issue with other softwares?

Thank you very much,

Fabio Spinnato

It would be helpful if you describe the data you're using. Are we talking about raw or zero-centered utility scores? It is quite normal to end up with negative utility for a specific concept you're measuring, so I'm not clear as to why you're getting this error.

I use Sawtooth software for conjoint, so I'm not familiar with how SPSS runs conjoint analysis.