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Jun 11, 2020 at 14:32 history edited CommunityBot
Commonmark migration
Feb 15, 2019 at 10:47 comment added sandrabee @COOLSerdash - thanks for your comments! They were helpful to me. So you would not even go for a all subset regression?
Feb 14, 2019 at 7:06 comment added COOLSerdash I would recommend against any stepwise procedure. It depends on what exactly your goal is. If you're interested in the evidence of associations between the grades and the variables, just fit a model containing all of them and report confidence intervals, p-values etc.
Feb 13, 2019 at 22:44 comment added sandrabee @COOLSerdash: thanks for your response. Could you recommend going for a stepwise linear model with crossvalidation?
Feb 13, 2019 at 15:47 comment added COOLSerdash If you have only one response per subject, a linear mixed model is not applicable. Just use a normal linear regression.
Feb 13, 2019 at 13:53 comment added sandrabee @COOLSerdash: Thanks, I am quite confused, yes. So thank you for clearing the fog... So if I model all variables as fixed effects and add the subjects as random effects, I get the error message "Error: number of levels of each grouping factor must be < number of observations" as for each of the 74 subjects there is one response per variable and the total study population is all 74 subjects. In another threat here it is mentioned "... if there is only one observation per level of the random effect, don't use lmer, and don't model the random effect." Any pointers?
Feb 13, 2019 at 10:40 comment added COOLSerdash You seem confused about random and fixed effects. From your question, I'd include all variables as fixed effects and just add a random intercept for each subject as random effect.
Feb 13, 2019 at 8:27 comment added sandrabee @COOLSerdash: many thanks for your comment! Was indeed helpful. I have edited the question now, as trying to use LMMs for this dataset is unclear with regards to nested and crossed random effects.
Feb 13, 2019 at 8:25 history edited sandrabee CC BY-SA 4.0
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Feb 9, 2019 at 21:20 comment added COOLSerdash I'd recommend sticking with the linear mixed model (lme4 package). These models are more flexible, lack some assumptions (sphericity) and are better in dealing with missing data.
Feb 9, 2019 at 15:57 history edited sandrabee CC BY-SA 4.0
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Feb 9, 2019 at 15:52
Feb 9, 2019 at 15:38 history asked sandrabee CC BY-SA 4.0