# Which distribution family for generalized linear-mixed model based on the plots?

I have a repeated measure study with continuous and two categorical predictors (time for repeated and group for control/experiment group. I checked the assumptions, and realized that there may be some problems to go with linear mixed-effects and decided to switch to generalized linear mixed effects models.

However, I cannot decide which family I should choose for the models. I have two models for two different continuous predictors. By the way, I checked the assumptions overall, not based on groups which I hope it is a better practice.

Model 1 = https://ibb.co/VLwTNq7

Model 2 = https://ibb.co/ZNFT8Hs

Just dependent: https://ibb.co/sWz44FW and its histogram: https://ibb.co/5n9mDf2 The outcome variable is Depression (measured repeatedly before and after neutral and negative stimuli exposure (between subjects). It was measured via a Likert-type questionnaire. We are looking for how adaptive/maladaptive effects pre and post depression after exposure to neutral and negative stimuli.

Which family should I choose?

– EdM
Jan 16 at 17:05
• Hello! Actually, I was going to ask you directly. The outcome variable is Depression (measured repeatedly before and after neutral and negative stimuli exposure (between subjects). It was measured via a Likert-type questionnaire. Rather than hypotheses, we are looking for how adaptive/maladaptive effects pre and post depression after exposure to neutral and negative stimuli. Jan 16 at 17:50
• Please edit the question to put that information, and the rest I asked for, into it directly. Comments are easy to overlook and can be deleted. Although helping with individual problems is an important part of the work on this site, it's also important to make individual questions and answers useful to later visitors. The more self-contained a question is, the better.
– EdM
Jan 16 at 17:53
• Thank you for making some initial amendments. What families have been considered (and why)? Why is the underlying random-effects structure used (and why)? Jan 16 at 20:58
• Hi. Actually, I don't know what family to consider. The question was about it. So, it is a right skewed dependent variable. We used random-effects because the participants in one of the groups and it is not important. Jan 17 at 12:38

Frank Harrell devotes several chapters of Regression Modeling Strategies and his course notes to ordinal regression. The R ordinal package implements ordinal regression for mixed models.