Re: [R] Two-way linear model with interaction but without one main effect

Thanks for the suggestion, Thierry. Nevertheless, in this example I'm not considering "shoe" as a random, nuisance factor with zero mean. I'm considering three specific shoe models, and I'm interested in modelling how the output changes between the different shoes for those grounds, given that the

Re: [R] Two-way linear model with interaction but without one main effect

Dear Helios, I think you rather want a mixed model with shoe as random effect. library(lme4) lmer(Y ~ Ground + (1|Shoe)) #the effect of shoe is independent of the ground effect or lmer(Y ~ Ground + (0 + Ground|Shoe)) #the effect of shoe is different per ground. Best regards, Thierry ir. Thie