what r model has proficiency as a factor when to add proficiency to r model r na proficiency na factor is proficiency a factor lmer proficiency factor is proficiency an effect what is proficiency score calculated for is proficiency a factor what is proficiency in mixed effect model? what is proficiency in r what is proficiency score what factors are included in mixed effect analysis does r consider proficiency as a factor is proficiency factor in r does proficiency become negative in r does proficiency include na in mixed effect modelling does proficiency become negative when lmer adds proficiency to a model does proficiency factor have a bic what is proficiency factor does proficiency score matter