Keith, thank you so much for the detailed answers.
It really helped me lots.
To provide more information, I am using CVA for my dissertation to reveal the preferences, not much focus on predictability.
This being said, although it may provide very little diagnostic value, I would need to pick one of the ways: adding at least three holdout fixed sets or reformat CVA to CBC data.
I looked for postings on the forum and technical papers in reformating CVA data into CBC for potential use in CBC model explorer, but couldn't find one.
My 15 CVA scenarios are 9 point RATING scale with paired concepts.
Would you please lead me a way to reformat the data?
If not, would adding 3 holdout fixed scenarios (assuming 3 is the enough number) at the beginning of the survey before the actual CVA scenarios be the only option?
Once again, thank you so much for any input or feedback.