In my research (based on an CBC) I applied conditional pricing to reflect a price-class (low, medium and high) at specific brand (Traditional, Favourite, Top and Signature). So I have three price point for four brand. Meaning that respondents were shown a different low price for example the Traditional brand than for the Favourite brand. For my research I make use of the logit, LCA and HB method to interpret the utilities.
My question is how I should interpret the part-utility scores of the main effects of brand and price on these methods. I am aware that I have to interpret the utility of a brand part-worth considering the average price that this brand was shown at. So, the brand part-worths are no longer disentagled from the price points. However I wanted to know how exactly to interpret these part-worths for the main effects of price and brand. In addition I wanted to know how to interpret the part-woth utilities when an interaction effect is present between the brand and price. Do I just add or subtract the part-worth of the interaction effect to the utility at the average price or is this calculated in a different way?