All Questions
50 questions
3
votes
1
answer
303
views
Finding the optimal structure of fixed / random effects in a 3 way full factorial repeated measures design with nlme/lme4
I’m looking for help in finding the best / optimal structure of fixed and random effects in my repeated measures experiment data along with an explanation on why do I choose one solution over the ...
CommunityBot
- 1
1
vote
0
answers
47
views
How to conduct post hoc paired comparisons for mixed effects model?
I am working with some biological data where I am trying to compare 5 categories of genes by expression which occur at different loci (locations on the chromosomes). I have samples from different ...
- 255
1
vote
1
answer
64
views
Testing assumptions for repeated measures ANOVA
I was wondering how to assess residual normality of a repeated measures ANOVA. In some threads, users refer to Venables and Ripley: Residuals in multistratum analyses: Projections and recommend to ...
- 102k
0
votes
1
answer
155
views
Help with lmer formula for a repeated measures ANOVA
This is my first repeated measures analysis.
Subjects in two groups exercise until "peak" level. Blood is taken at baseline (prior to exercise), peak, 2hrs post, 24 hrs post, and 72hrs post. ...
- 102k
2
votes
2
answers
340
views
What should be normally distributed for a two-way repeated measures ANOVA? R
When running a two-way repeated measures ANOVA, should:
A) the independent varibles be normally distributed?
B) should the scores between the variables be normally distributed?
Overall: should the ...
- 1,057
1
vote
1
answer
118
views
How to specify a repeated measure in a Mixed Effect ANOVA?
I am trying to run a Repeated Measures Mixed Effect ANOVA in R. However, the syntax of the code is really tricky and it seems like there is not a lot of clarity on how to run it as I do my research.
...
- 102k
2
votes
2
answers
275
views
Specify an lmer model for fully crossed data with replications
I have experiment data with multiple independent variables:
shape - 2 factors
color - 2 factors
...
- 6,650
0
votes
0
answers
67
views
LMER returns errors, but Repeated Measures ANOVA on the same data doesn't, why?
everyone!
So, I've been trying to fit a LMER for my data, which I fully described in this post .
This post, therefore, is a follow-up from the previous one. There's something intriguing me, I don't ...
- 843
0
votes
2
answers
310
views
Anova and mixed effect models (lm4 / nlme) return complete different effects
As a continuation of a previous topic, I would like to address a similar experience.
Subjects completed an experiment in which their electrodermal activity was recorded. For each subject there are 72 ...
- 82.8k
14
votes
2
answers
7k
views
What is the lme4::lmer equivalent of a three-way repeated measures ANOVA?
My question is based on this response which showed which lme4::lmer model corresponds to a two-way repeated measures ANOVA:
...
CommunityBot
- 1
1
vote
1
answer
70
views
Which is the best dataset for an anova; raw or blup values?
I have a set of 150 rice varieties, which have different environmental classifications. I have measured a trait, y, on four repeats of each variety.
I want to test the effect of environmental ...
- 82.8k
2
votes
1
answer
424
views
How to conduct a two-way repeated measures ANOVA in R
I'm sorry if this question has been clarified in another post. I've looked around for some time and have been unable to find an answer.
I'm conducting research to evaluate heart function before and ...
- 20.9k
4
votes
1
answer
461
views
Why does this error occur with my linear mixed models?
I am attempting to run linear mixed effects models using the function lmer() in order to analyse the effect of the direction of change (single categorical fixed effect) in weather parameters over a ...
- 65.9k
2
votes
1
answer
769
views
Very different results with ezANOVA and LMER in R
I have a repeated-measures design, so I use ezANOVA. However, I was interested in a numeric (ordinal) predictor, so I ran two models: with ezANOVA (ez package) and lmer (lme4 + lmerTest). The results ...
0
votes
0
answers
101
views
Mixed model instead of RM anova?
I have data points collected at 4 time points for $N$ subjects. I need to understand if there is a difference in mean readings at these 4 time points, and also if age and gender influence these mean ...
- 63
3
votes
1
answer
2k
views
repeated-measures linear mixed-effect model
I have two soil treatments: CT and NT.
For each treatment, I have 11 CO2 measurements taken in 7 times, i.e. 11 "replicates" for 7 dates.
I'd like to evaluate if the measurements are different in ...
- 65.9k
11
votes
1
answer
4k
views
Equivalence between a repeated measures anova model and a mixed model: lmer vs lme, and compound symmetry
I have some trouble obtaining equivalent results between an aov between-within repeated measures model and an lmer mixed model.
...
1
vote
1
answer
136
views
Is different sample size okey for a Repeated measure-between Subject experiment?
I have data from a between-subject experiment (Repeated measures, two conditions). Condition A has 15 participants while condition B is with 19. The difference is due to missing data.
My aim is to ...
- 21.5k
59
votes
2
answers
113k
views
Using lmer for repeated-measures linear mixed-effect model
EDIT 2: I originally thought I needed to run a two-factor ANOVA with repeated measures on one factor, but I now think a linear mixed-effect model will work better for my data. I think I nearly know ...
- 41
4
votes
1
answer
5k
views
Why use Linear Mixed Models instead of Repeated Measures ANOVA?
Well, here's some background before the question:
I have an experiment where I evaluate the heart rate of subjects in 4 different conditions (4 time points). The subjects also answer a psychometric ...
11
votes
1
answer
736
views
Repeated measures anova: lm vs lmer
I'm trying to reproduce several interaction test between with both lm and lmer on repeated measures (2x2x2). The reason I want ...
- 613
4
votes
0
answers
221
views
Syntax differences between aov and lmer for two-way repeated measures design
I'm working with the following data frame using R. It consists of measurements obtained from 7 subjects with two independent variables (IV1 and ...
- 107k
24
votes
2
answers
39k
views
Repeated measures ANOVA with lme/lmer in R for two within-subject factors
I'm trying to use lme from the nlme package to replicate results from aov for repeated ...
- 107k
10
votes
3
answers
407
views
Bacteria picked up on fingers after multiple surface contacts: non-normal data, repeated measures, crossed participants
Intro
I have participants who are repeatedly touching contaminated surfaces with E. coli in two conditions (A=wearing gloves, B=no gloves). I want to know if there's a difference between the amount ...
- 86.6k
3
votes
1
answer
2k
views
RM ANOVA: time as continuous or categorical?
I am using the lme() funtion in R (from nlme package) to perform a Repeated Measures ANOVA. Here's the formula
...
- 165
2
votes
1
answer
2k
views
r - 2-way Repeated Measures ANOVA - different degree of freedom among ezAnova, aov and lme [closed]
I would like to run a simple repeated measures ANOVA with 2 factors (Food & Drink).
Let's have a dummy df:
...
- 11.6k
2
votes
0
answers
1k
views
Two factor ANOVA with repeated measures by mixed model (lmer) [duplicate]
I did a simple experiment with trees: 5 species (sp) and two management (trt). I assessed the diameter (...
3
votes
0
answers
999
views
Denominator df's depending on random structure in a mixed effects model - how to report them?
In my current research I'm using linear mixed effects models to explain reaction time data from a repeated measure design.
When testing different models for best fit I checked various random ...
- 557
12
votes
2
answers
20k
views
Are degrees of freedom in lmerTest::anova correct? They are very different from RM-ANOVA
I am analyzing the results of a reaction time experiment in R.
I ran a repeated measures ANOVA (1 within-subject factor with 2 levels and 1 between-subject factor with 2 levels). I ran a similar ...
- 107k
2
votes
0
answers
406
views
repeated measures four-way Anova lmer or ezAnova?
can anyone help me to figure out what is the best way to run 4-way repeated measures ANOVA? I have four within-subject factors: Block, Reward, Congruency, and quan (quartiles). In addition, there a ...
- 121
8
votes
1
answer
3k
views
Are aov() with Error() same as lmer() of lme4 package in R?
Are following 2 models really the same?
...
- 107k
1
vote
1
answer
1k
views
Different results obtained with lmer() and aov() for three-way repeated-measures experiment
My question concerns results from one of my experiments, where analyzing the data with RM-ANOVA (using either ezANOVA or aov on ...
- 107k
14
votes
1
answer
1k
views
Equivalence of (0 + factor|group) and (1|group) + (1|group:factor) random effect specifications in case of compound symmetry
Douglas Bates states that the following models are equivalent "if the variance-covariance matrix for the vector-valued random effects has a special form, called compound symmetry" (slide 91 in this ...
- 20.6k
3
votes
0
answers
363
views
3-way repeated measures ANOVA with nlme::lme assuming compound symmetry
For teaching purposes I want to show the similarity between a 3-way repeated measures ANOVA aov(y ~ A*B*C + Error(Subject/(A*B*C)), data) and the corresponding lmm ...
- 6,650
1
vote
0
answers
112
views
Within-subjects ANOVA with lme and multiple fixed variables
I am looking at the relationship between age and DNA methylation in teeth samples. We collected three tissues from every tooth (dentin, cementum and pulp), but were unable to get measurements from ...
- 121
5
votes
0
answers
2k
views
When using repeated-measures ANOVA in R, what does it mean to specify Error(subject) instead of Error(subject/(A*B))?
For a two-way repeated measures design, we can specify the model using aov in the following fashion:
...
- 107k
3
votes
0
answers
1k
views
Difference in post-hoc tests for repeated measures ANOVA and linear mixed model
I have noticed a difference in post-hoc results produced from a repeated-measures ANOVA and a linear mixed model.
Here is reproducible code:
...
- 31
28
votes
2
answers
5k
views
Does it make sense for a fixed effect to be nested within a random one, or how to code repeated measures in R (aov and lmer)?
I have been looking through this overview of lm/lmer R formulas by @conjugateprior and got confused by the following entry:
Now assume A is random, but B is fixed and B is nested within A.
...
CommunityBot
- 1
1
vote
1
answer
2k
views
Within-subjects contrasts in repeated measures anova with unbalanced design [closed]
I would like to reproduce the standard output of a repeated measures anova in SPSS with R. For a balanced design (i.e. equal group sizes) I can exactly reproduce the SPSS output of the within-subjects ...
- 33
4
votes
0
answers
2k
views
Testing for differences between time series with many timepoints
I think the easiest way to describe my question is with plots.
I've run an experiment where I recorded data from animals' brains (EEG) at 6 depths. The animals are recorded at baseline for 25 minutes,...
- 82.8k
4
votes
0
answers
177
views
aov() and lme() give completely different results in analyzing repeated measures [duplicate]
I have data consisting of two measures per subject (variable score, measured at Day 0, and Day1 per each subject).
There are two groups, and each subject belongs to one of them (variable Group).
I ...
4
votes
1
answer
2k
views
Model selection: testing the need for random-effects terms in longitudinal data
I have longitudinal data set where each participant was observed for 12 weeks.
I followed this paper: Bliese, Paul D., and Robert E. Ployhart. "Growth modeling using random coefficient models: Model ...
- 47.4k
26
votes
2
answers
23k
views
Why do lme and aov return different results for repeated measures ANOVA in R?
I am trying to move from using the ez package to lme for repeated measures ANOVA (as I hope I will be able to use custom ...
- 107k
2
votes
1
answer
574
views
lme versus aov repeated measures variance specification
I am performing a repeated measures ANOVA in R, where the experimental design is composed of a between-subjects factor (Prodotto, three levels), the within-subjects ...
8
votes
1
answer
4k
views
Two-Way Repeated-Measure design with lme4
I would like to model a treatment effect in two different groups, controlled for some co-variates (like age and education), and I assume that a two-way repeated-measure Anova would be the right ...
CommunityBot
- 1
2
votes
1
answer
10k
views
How to assign degrees of freedom for two-way ANOVA with two within-subjects factors?
I have an experiment with 44 subjects and two within-subject factors, condition (3 levels) and round (6 levels). It is fully crossed such that each person completes one of each task condition in each ...
- 131
1
vote
0
answers
227
views
What is the equivalent of a repeated ANOVA using a mixed effect model with lme?
I have a data frame with this structure:
...
- 2,949
2
votes
1
answer
2k
views
ezAnova vs. lme for factorial repeated-measures design: results differ, why?
I have used lme and ezAnova to analyse data from a 2$\times$3 repeated-measures experiment. Theoretically those are two ...
- 23.6k
0
votes
2
answers
2k
views
Repeated-measures ANOVA looking at interactions for a BACI design in R
Here are my data:
...
CommunityBot
- 1
9
votes
2
answers
6k
views
How to deal with repeated measurements in the same condition of a factorial experiment?
I am in Psychology and trying to explore the utility of mixed modeling for analyzing my repeated-measures data in a factorial experiment. The primary reason for using mixed models is that I would like ...
- 573