How to model effect of continuous predictor on category order data in R?

I am working on building an appropriate model for sequential categorical data in R. Here is the set up: I have a sequence of categorical predictions whose order I want to analyze. I also have a continuous predictor that is hypothesized to affect transition frequencies between categories. In addition, the data comes from an experiment … Read more

Define model and interpret multinomial regression

Question What should my (multinomial logistic regression) model look like for analysis of the data described, and how can I interpret it and report it in an acceptable way for journals that typically expect a P value. Background I’m a grad student. I have taken the only stats course available in my department, so I … Read more

is it correct to analyse a mixed model interaction between a numeric and a factorial variable by using a bootstrapping method?

I am analysing a mixed effect model: library(lme4) lmm_treat <- lmer(total ~ TREAT * POS + (1|NO_UNIT), data=data) DESCRIPTION OF THE MODEL: “total” is the value I am comparing between the treatments (TREAT) and temperatures (POS). TREAT is used as a factor and POS as numeric (and I cannot change it to factor due to … Read more

Conflicting results of summary() and anova() for a mixed model with interactions in lmer+lmerTest

I recently came across what I think may be a problem in how the anova() function from the lmerTest packages computes its F-statistics and corresponding P-values for fixed effects from mixed-effects models. Let me start by saying that I know of the controversy surrounding calculating P-values from mixed effects models (for reason discussed here). Nonetheless, … Read more

Pseudoreplication & mixed effects with highly unbalanced dataset

I have a dataset with ~250 data points. When I regress Y on X1 and X2, X1 is a significant predictor of Y. However, about half the 250 points are pseudoreplicated; they come from locations with >1 observation and are not strictly independent. Normally, I would include a random slope for X1 and X2, but … Read more

Calculating DeltaAIC

I’ve been advised by a colleague that when performing backwards elimination for model selection using AIC as my criterion, I should remove terms individually – starting from the most complex interaction, and working down to the main effects, comparing the AIC for the reduced model and comparing it to the full model (the original model … Read more

Significance testing of intercept term of random effects model, where h0 p is not 0.5

Suppose subjects do a series of 3-alternative oddity trials (i.e., picking the odd-man-out from 3 samples is “success”). The null hypothesis probability of success is 1/3. I would like to know whether the subjects can pick the odd-man-out significantly more often than predicted by chance. I think the way to go is to construct a … Read more

random effect logistic regression in R [closed]

Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it’s on-topic for Cross Validated. Closed 2 years ago. Improve this question I have a response variable y ranging from 0 to 7. The data nicely show a S-shaped curve and I would like to … Read more

Why include quadratic terms in interactions in lmer?

Can someone please clarify whether I need to include a quadratic term in interactions instead of just using the linear term? I have a mixed model with a logarithmized response variable and three predictors. One of the predictors (=time) has a curved relationship with the response. I also have two important interactions of time with … Read more

Two factor ANOVA with repeated measures by mixed model (lmer) [duplicate]

This question already has answers here: Using lmer for repeated-measures linear mixed-effect model (2 answers) Unbalanced mixed effect ANOVA for repeated measures (1 answer) Closed 3 years ago. I did a simple experiment with trees: 5 species (sp) and two management (trt). I assessed the diameter (diam) through the time (month=1:24) and I’m interesting in … Read more