All Questions
90 questions
0
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0
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12
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Meaning of lognormal in performance::check_distribution() in R [duplicate]
I modeled my data using lme4:lmer() function. Since the model's performance was not satisfactory, I used function performance::check_distribution() which suggested that both predicted distribution of ...
- 1
1
vote
0
answers
93
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Degrees of Freedom in Emmeans
I am using the 'emmeans' package in R to compute estimated marginal means for my (liner mixed-effects) model. However, I am enountering a warning message related to the number of observations ...
- 11
0
votes
1
answer
51
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Post-hoc for GLMM with polynomials/splines
I'm trying to do a post-hoc on my GLMM but I'm not sure I'm doing it right.
I test the effect of continuous variables X and Y on a binary response Z with my IDs as a random effect with this code:
<...
- 123
0
votes
0
answers
70
views
Effect size for marginal means of a model with an interaction term
I'm wondering what is the correct way to calculate the eff_size() of a lmer model with an interaction term. I'm following this ...
- 843
2
votes
0
answers
80
views
Computing Bayes Factors for pairwise comparisons, linear mixed models
A reviewer asked for either Bayes Factors or effect sizes for pairwise, planned comparisons in linear mixed modeling. In the experimental design, I have 30 participants, one fixed factor (repeated ...
- 135
2
votes
1
answer
234
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Help understanding Cohen's D for pairwise comparisons in lme
I've been asked by a reviewer to provide effect sizes for pairwise, planned comparisons. In the experimental design, I have one fixed factor with three conditions (Consistency). Passage & Subject ...
- 135
0
votes
1
answer
71
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Confidence Intervals Overlaping Although Significant Effects in glmer in R
Below is the output of a glmer:
...
0
votes
1
answer
678
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Significant pairwise comparisons from emtrends but marginal means are not-significant?
I'm quite new to this type of statistical analysis, so apologies if the question comes across as silly. I'm currently fitting a mixed lmer with two categorical (condition and outcome; each with 2 ...
1
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0
answers
97
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Compare quadratic coefficients between group levels from mixed effects model?
I'm hoping I can find some advice on this question. I have repeated measures of an outcome variable yvar where the trend over ...
- 133
0
votes
1
answer
163
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Emmeans and lmer with quadratic and cubic interaction
I have an experiment where I predict that the two levels of my Cond variable (effect coded as -1 and 1) will have different trends over time on my EDA_cs outcome variable (skin conductance). ...
- 111
0
votes
0
answers
299
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R: emtrends pairwise contrast results change when testing slopes against 0 or 1
When performing post-hoc simple slope analysis on my linear mixed effect model in R using emtrends(), I noticed that pairwise slope comparisons showed differences in the significance when I tested all ...
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1
vote
1
answer
33
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Is it possible to conduct post hoc eventhough there is no significant interation between the levels of factors in lmer results?
I want to conduct a statictical analysis on reation times(dependent) between two groups of people.
suppose the factors are: A, B, group
Is it possible for me to conducting a posthoc test(by using ...
- 11
2
votes
1
answer
1k
views
What is the difference between z.ratio and t.ratio in the pairwise comparison output using emmeans function?
I don't understand why the output of pairwise comparison using emmeans function is z.ratio when analysing response time data. What is the difference between z.ratio and t.ratio? And is this ...
- 21
2
votes
1
answer
222
views
What is the difference between p-values in summary() and p-values given e.g. by emmeans?
I am working on a binomial mixed model. I want to analyse the use of a certain construction by students. My response is CONSTRUCTION (two levels: THAT/NO_THAT). My predictors are both categorical (...
- 51
1
vote
1
answer
171
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how to perform multiple comparisons on a linear mixed model with unbalanched set of groups
I have built a linear mixed model (rt.m6) with 2 fixed factors, namely condition and suffix, which also interact with each other. However, my experimental design isn't fully crossed, meaning that not ...
3
votes
1
answer
1k
views
What's the appropriate effect size estimate (and power analysis) for post-hoc regression?
I've seen some similar (ex ex2) questions, but hopefully this is not a duplicate. As it is mentioned in one of them, I'm using eemmeans to do pairwise comparisons ...
- 843
1
vote
1
answer
1k
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emmeans: interaction contrast with continuous variable - same se, t- and p-values?
I am analysing my own data with a linear mixed model and estimated marginal means and have made a strange observation. I have run an experimental study with three treatment groups, measuring a ...
- 75
1
vote
1
answer
505
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Posthoc analysis LMM for interaction containing a factor with 3 levels
I am fitting a Linear Mixed Model using the lmerTest package. I have two fixed effects: group (categorical, 2 levels) and period (categorical, 3 levels). I have an interaction term between the two ...
- 25
0
votes
1
answer
337
views
How do you conduct contrasts (pairwise comparisons) for a lmer() when your IV is continuous?
I am using lmer() to run an analysis with one categorical variable with 2 levels (task) and one continuous variable (farFC). Below is the model:
...
- 113
1
vote
1
answer
55
views
Linear mixed effects analysis in R: Compare estimates of different reference grids (estimate at one value of a continuous variable versus another)
I'm performing a linear mixed effects analysis to find out how locMap (categorical) and frequency (continuous) influence voltage (continuous):
...
- 33
0
votes
1
answer
406
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emmeans: Is bias adjustment appropriate?
I have the following model. The outcome, prop_correct, is a proportion of words correctly identified by participants in 5-word sentences (0 - 1) which is logit-transformed. Fixed effects include ...
5
votes
2
answers
195
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No variance in binomial glmer yields problematic CI
I have a glmer with a binomial response variable and two binary predictor variables, where there are no observations for one of the four groups. I used ...
- 329
1
vote
1
answer
357
views
Problems with emmeans if RE-adjustment and backtransformation from logit
In an experiment (4 sessions, 2 groups), subjects try to remember words.
We want to test
H1: the overall (marginal) main effect of group
H2: the specific interaction contrast of group and sesson1 _ 2
...
- 21
1
vote
1
answer
313
views
Calculate contrasts from lme model across specified timepoints
I have an MMRM with the below structure:
...
- 125
1
vote
1
answer
875
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planned contrast with **emmeans** on interaction term in mixed model
I think this is simple: I want to test if a treatment (that I know a priori does something) is stronger in one group vs. the other (in the presence of random effects). This seems like it should be ...
- 353
5
votes
1
answer
1k
views
R pairs function, adjust, tukey/tukey-kramer?
In the 'pairs' function when doing pairwise comparisons after emmeans, tukey is set as default for adjustment of p-values. But what type of tukey is used, is it tukey-kramer? How can I know this? If ...
- 197
0
votes
0
answers
72
views
How to compute Cohen's d and p-value for comparison of least squares mean from two different mixed models?
I have two randomly assigned treatment interventions (A and B), and two subgroups of individuals (X and Y). This is a longitudinal study with dropout. I want to test whether the outcomes of ...
- 31
1
vote
1
answer
706
views
huge degrees of freedom for post-hoc tests of lmer model using emmeans
I have a trial-wise linear mixed model with a categorial between-subjects factor group (A vs B) and two categorical within-subjects factors itemEmotion (neutral vs. negative) and neuralArea (frontal ...
- 45
1
vote
2
answers
887
views
How to do a follow-up comparisons/contrasts for a 3-way interaction with 2 numeric predictors?
I am having a hard time doing follow-up (post-hoc) comparisons for a 3-way interaction of 2 numeric predictors and one factor in a linear mixed model. It’s a longitudinal study where we have patients ...
- 55
2
votes
1
answer
734
views
How to obtain contrasts for constrained longitudinal data analysis?
I would like to apply a constrained longitudinal data analysis (cLDA) with a linear response variable of the form, y ~ Time + Treatment:Time + (1 | ID). I am using &...
- 227
0
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0
answers
30
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Df calculations seem off in lmer with 3-level categorical predictor comparison
This is a MLM analysis of a physiological variable (so big dataset) with a time x condition fixed effect, where condition has 3 levels. Model code is:
...
- 111
2
votes
1
answer
3k
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Probing categorical (3 levels) x continuous var with emmeans
I am trying to probe the following significant interaction between Condition (categorical, three levels) and time (continuous) using R emmeans package:
Original formula for the model was:
...
- 111
0
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0
answers
165
views
pairwise comparisons, emmeans or by hand
I have an lmer model with one categorical variable and several continuous variables. The results are as follows:
...
- 45
0
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0
answers
250
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0
votes
1
answer
252
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Linear mixed models - interaction between scenario and group with four levels - how to inspect
I have data with which I inspect if there is a difference between two scenarios in experienced temporal demands. In addition, there are four different roles (AO, RO, TO, VP) participants are assigned. ...
- 77
0
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1
answer
221
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Different p-values for simple slope analysis after dummy coding and contrast coding using robust lmer
I want to average the effect of some continuous predictors on the outcome variable and so I used contrast coding as here (https://towardsdatascience.com/how-to-correctly-interpret-your-continuous-and-...
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3
votes
1
answer
51
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nlme model specification and estimation of empty cells using emmeans
I have a data set with 20 users who were exposed to three levels and two variants (except the low level was only exposed to one variant). There are two measurements for each combination. Below are ...
- 7,470
4
votes
1
answer
1k
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Different ways to include pre-test performance as a covariate in a linear mixed-effect regression. Which is correct?
I have a pre-post experimental design, where I have measured participants' performance in three courses (tasks; A, B, C) at both pre and post-test. The study is a learning experiment. 60 elite alpine ...
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3
votes
1
answer
352
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Difference in slope in longitudinal study
I have a longitudinal study where subjects are measured at given time points and a response is recorded. Each subject belongs to one of three groups (A, B, C) and I'm interested in whether the slope ...
- 5,349
1
vote
0
answers
620
views
emmeans post-hoc comparison of model with interaction and control variables
I am using this mixed model including fixed effects and random intercepts and slopes:
...
- 11
0
votes
0
answers
180
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Interpretation of discrepancies between contrasts comparisons in lmer and emmeans
I have the following model with 4 levels under the Group factor variable and 3 levels under Cue_Type.
...
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2
votes
2
answers
975
views
calculate adjusted p and t value after Bonferroni Correction
I am using linear mixed effect models to analyse my data. I am looking at how 4 independent variables might affect 5 dependent variables. I read an article by von der Malsburg and Angele (2017) which ...
- 373
1
vote
1
answer
774
views
How to Compare Different Treatment Levels to Control in Linear Mixed-Effects Model?
I've run a human subjects study where participants answer a series of questions with a decision aid. In addition to the decision aid I have different "improvements" to the decision aid that ...
- 11
0
votes
0
answers
38
views
Statistitical differences pairwise comparisions on binomial data
I am running a inhibition of growth assay on bacteria on R. I've got a dataframe with the different bacteria and different concentrations, and my response variable, inhibition, being 1 if there is ...
3
votes
1
answer
2k
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What DF do you use for effect size calculation using emmeans with a crossed mixed-effects regression?
The emmeans vignette shows that we need to declare edf for calculating effect size. I just have no idea where to get this?
https://cran.r-project.org/web/packages/emmeans/vignettes/comparisons.html
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2
votes
1
answer
1k
views
How ti specify contrasts for lmer model
I am using lmer in R to check the effect of treatment and a group on some result (y).
In my data (dat), there are 3 categorical variables and a continuous response variable:
1 id
1 treatment variable ...
- 21
0
votes
0
answers
455
views
Pairwise comparison of numeric fixed effect of linear mixed model
Using the sleepstudy data from the lme4 package I want to do pairwise comparison using the emmeans package.
This is the model:
...
2
votes
0
answers
373
views
Warning message after running emmeans in R
I was doing a tukey-adjusted comparison among 3 levels of a factor (“Factor B”) using the emmeans() function in R and got the following warning:
...
- 31
0
votes
1
answer
207
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emmeans doesn't show the correct output
I am running the following LMER model with Place (five dummy-coded levels: bilabial, dental, retroflex, palatal, and velar) and Laryngeal (three dummy-coded levels: voiceless unaspirated, voiceless ...
3
votes
1
answer
3k
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emmeans output interpretation of a glmer fit with nesting
I have read that the interpretation of generalized linear mixed models (GLMM) at the response level is more complex because the back transformation is nonlinear and the random terms do not play a ...
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