who first introduced linear models which psychologist invented the random effects model when were random effects models first used who first compared linear and random effects models? who first introduced mixed effect linear regression? who introduced linear model who first introduced linear models? who first introduced linear model who first introduced linear models when was the first linear model introduced who first introduced linear models who was the first to propose linear models with fixed or random effects for longitudinal data? when did linear and mixed effects models come out what year was random effects introduced what was the first linear model who first introduced linear models who is the first linear model who was the first to use linear models? who were the first to introduce linear model and fixed effect who created linear data