I have a question regarding the usefulness of covariates in my ACBC HB estimation. Here's an interesting excerpt from the CBC/HB manual:
"If the percent of draws (associated with a part-worth utility) that have the same sign is 95% or greater, this is often taken as evidence that this realization of the covariate has a significant effect (90% confidence level, two-tailed test) on the part-worth utility estimate. If a relatively large number of columns for a covariate have significant weights, then this gives evidence that the covariate is useful."
I have a couple of covariate candidates, but it's tough to judge whether they truly make a difference or not. How can I decide whether or not to include a particular covariate? If e.g. 5 out of 18 columns are significant (> 95% same sign), is that unrelevant? What could be a threshold here to make a decision?