Question model information linear mixed models JASP

Comments

• patc3

  November 15

  my guess is that you need to look at Model -> Random effects:

  

  By default JASP has the very bad default behavior of adding all possible random effects, whereas you specify those manually in SPSS or R (and probably rarely specify them all)
• EJ

  November 15

  But is this bad behavior? What alternative procedure would you recommend? Not give any output until these effects are specified as fixed or random?
• patc3

  November 15

  I would do random intercept personally

  it's bad because it rarely runs (e.g. if you reproduce the example in the data library from scratch by going into mixed -> linear, it throws an error until you remove all random effects but the intercept, as in the example), and because that's rarely what the user wants to do
• patc3

  November 15

  it's like JASP is taking the approach of model pruning rather than model building, but it rarely runs out of the box because of this, and not everyone is savvy enough to know what the error means...
• EJ

  November 15

  Yes but we have to do something.
• patc3

  November 15

  random intercept
• EJ

  November 15

  So set everything else to fixed by default? But this seems to go against the popular mantra to "keep it maximal"
• František

  November 17

  There is a lot of discussion in the literature how to properly specify random effects structure. However, one thing that majority of people agree on is that random intercept only models are suboptimal as they lead to poor coverage and inflated type I error rates. We therefore avoid using them as the default option.

  We decided to use of the 'keep it maximal' recommendation i.e., fiting as complex random effects as possible. Of course, models should be simplified if they fail to converge (which is indicated by a warning message).

  
  

  (We also automatically drop random factors for fixed effect predictors that do not vary between subjects, i.e., between subject factors, but that is also indicated in the messages)

  
  

  Cheers,

  Frantisek
• daniquelatorre

  November 28

  Thanks for the answers. Do you have references that support the LMM model in JASP?
• TarandeepKang

  November 28

  The idea of "keeping it maximal" as much as justified by the design, comes from this paper.

  Barr DJ, Levy R, Scheepers C, Tily HJ. Random effects structure for confirmatory hypothesis testing: Keep it maximal. J Mem Lang. 2013 Apr;68(3):10.1016/j.jml.2012.11.001. doi: 10.1016/j.jml.2012.11.001. PMID: 24403724; PMCID: PMC3881361.

  
  

  I hope this helps!

  
  

  PS, I'm not a developer or a member of the team, just another JASP user