I am working on sales of a B2B company and I have sales volumes of different customers at different price points. Some customers, however, purchased at only a single price point.
I'm trying to identify the effect of price on sales volume using a mixed-effects model (varying slope, varying intercept), where each customer is a "group"
Eg. Sales ~ Price + (1+Price|Customer)
My question is - What happens when certain customers have only one price point (ie. the independent variable does not change). Would these customers affect the fixed effect of 'Price' (do they bring the slope of the fixed effect closer to zero)? Is it more appropriate to remove these customers from my analysis?