CBC/Hb - Covariates in the alpha file

Question

Hello everyone,


I am really new to CBC/HB and I conducted an analysis with three conditions. I put the conditions as Covariates.
When I checked the alpha file, I saw that there are columns for intercept for each attribute level, for condition 1 and condition 2, but I don't unterstand why condition 3 is not shown or do I interpret it wrong.
I want to conduct a t-test to see if there are significant differences for price in the upper models.

Maybe you could help me.

Best regards
Jana

Answer 1

Level 3 respondents for your covariate (the last level of any categorical covariate) are represented in the intercept values.  Levels 1 and 2 respondents are represented by the intercept values plus the alpha values shown in the alpha file.

So, for example, if for Brand 1 the intercept value was +1 and the covariate value for level 1 respondents was +2, the total alpha value (mean population parameter) for level 1 respondents would be 1+2=3.