# Tagged Questions

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### How to deal with unbalanced group sizes in mixed design analysis?

I have 2 x 2 x 2 mixed design with two between subject factors (sex, organizer) and one within subjects factor (task). The group sizes of the 'sex'-factor is unequal. When I perform a factorial ...
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### Determine individual consistency from mixed model?

To investigate the difference between three tasks I tested 30 individuals on each of the three tasks and ran the linear model as follows: ...
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### How do I model repeated measure + random effects with SPSS mixed

I'm having trouble understanding what a correct model for my data should be, and also if it would even be a good idea to make it a single model. At the basis it is a rather simple regression model ...
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### Choosing test for longitudinal, repeated measures and clustered data

I'm a researcher within cardiovascular medicine, currently working on a study in endocrinology (diabetes). I have the following challenge, which I have discussed with several statisticians who all ...
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### Which statistical analyses should I use?

I want to compare data from a treatment group vs a control group over time (baseline, 1 yr, 2 yr). The measurements are repeated for all subjects across all time points (i.e., all participants ...
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### Analysis of longitudinal data with very few points

I'm trying to analyse some data I've recently gotten my hands on, but I'm not entirely sure which model to use. One suggestion has been a Mixed Model, Repeated Measurements ANOVA, but I'm not sure if ...
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### What is my experimental design?

I am very new to mixed/multilevel models. I have an experiment where we measured 2 scale variables (varA and varB) in 2 different groups of subjects (control and treatment) at 4 different time points. ...
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### Prediction based on repeated measure with binary outcome

I'd like to make a prediction about a subject's likelihood that a certain outcome will occur based on a series of measurements taken over time. The easiest way to explain the problem is as follows. ...
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### Linear mixed model for repeated measures analysis with missing values

we have ran an experiment where we compared three interaction techniques for a 3d docking task. So we had two factors: the aforementioned technique type and a factor representing the direction ...
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### Fitting a multilevel model to data from an experiment with between- and within-subjects factors

I have data from an experiment that I would like to analyse with a multilevel model. In the experiment, participants read 1 scenario about a person and they had to answer a couple of questions about ...
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### Repeated measures across time, two treatment groups

I'm having difficulty modeling somethingâ€¦ I think it's fairly simple, but I'm just not confident enough in my ability. I setup an experiment with two treatment groups, six replicates in each ...
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### Personality traits as fixed vs. random effects in a repeated measures mixed model

We performed a randomized controlled trial. I am interested in anxiety levels (dependent), treatment (meds vs. ultra-dance therapy), and personality variables (agreeableness, neuroticism, weeaboo). We ...
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### Help with repeated measures regression (in R)

I have some small datasets (example data given below) where I am interested in describing relationships between $Y_1$ and $Y_2$ across a gradient $X$ at two time points (date = "early" & "late"). ...
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### Mixed effects model or mixed design ANOVA in R

I'm wondering if you could quickly advise on the best statistical analysis for my data. I have a designed experiment with 12 plots within one larger area. This area was blocked into 6 to overcome ...
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### Interpretation of mixed model with repeated measures

I have performed the following experiment: Two genotype groups of two different ages were monitored in the presence of three drugs one after the other. So, each subject after a control period received ...
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### Correctly specifying temporal pseudo-replication in a mixed effects model in R/nlme

I would like to correctly specify that my data is temporally pseudo replicated in a mixed effects model in R using lme() of the ...
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### Post hoc tests for robust mixed design ANOVA using R

Is it possible to compute the function mcp2atm with unequal sample size? I ran the robust Mixed Design ANOVA by using tsplit and ...
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### Is it possible for my mixed model results to be the same as those for a repeated measures ANCOVA? Why don't I get the same results? SPSS

The experiment: Two groups of children perform tasks with three levels of difficulty at two different time points and brain activity is measured. All of the children perform all of the tasks and do so ...
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### Adding between subject factor reduces p value of main effect?

I'm investigating the effect of tumor location on mood (depression / anxiety) and also seeing if time has an effect at two intervals (t0 and ...
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### A repeated-measures LMM… Am I understanding this correctly?

So I've been reading West et al's book on Linear Mixed Models as I'm trying to figure out how I should analyze my data, and I was wondering if I've correctly understood what I've ready so far. So, I ...
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### Specifying a correct full model for an unbalanced repeated measures design in R lme4

Recently, I have done a fairly complex experiment, and I am having trouble coming up with a model that is suitable for the data. I have spent a few days reading about, e.g., when random effects should ...
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### Book on Repeated Measure Analysis

Can anyone recommend a good book or some other reading materials on repeated measure analysis using mixed model.Thanks. Hanna
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### Mixed models and normally distributed random effects

I am attempting to analyze some data that includes 10 repeated measurements on 10 different samples. This would normally require using mixed models, and I have attempted to model these using ...
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### Models with Nested Effects

I am having difficulty understanding nested effects. Suppose 20 people each are assigned to treatment groups A B C and D. Would it be correct to say that Person is nested within treatment group? So ...
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### How can I analyse results from repeated measures of mixed design in R

I want to investigate performance in a learning test, where my test animals have been submitted to a number of trials within test day over several test days. I want to investigate if there is an ...
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### Error term in repeated measures ANOVA in R

I am having problems with defining the error terms for a two way repeated measures ANOVA in R. My data consists of wood density estimates for three radial positions (inner, middle, and outer) along a ...
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### Mixed model repeated measures, nested

I have a study in which I have 3 groups of crews (4 crews in each group) in which there are two people (L/R). Each crew experienced 4 lighting treatments (D1-4), once in one position, and again in ...
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### Comparing groups at different time points within repeated measures study using SPSS

I have done a RCT (randomized control trial) of an intervention (which is of 6 week duration) versus control. The outcome measure (an exercise test) has been tested pre-intervention (Pre), immediately ...
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### How to determine post-treatment weight with uneven time points?

really appreciate your input on how to deal with uneven time points and missing data in a single-group repeated-measures design. BACKGROUND: A group of 220 subjects went through a 4-month weight loss ...
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### Interpretation of interaction and main effect in a mixed model when one is significant and the other is not

I have repeated (x4) measurements on 90 subjects. The outcome is zero inflated. The model output gives these estimates: ...
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### repeated measurements study using JMP - how to make a difference plot when data is unbalanced

My study is a repeated measurement design where I'm going to show reproducibility of pulse wave velocity measurements on minipigs. I have read a lot of articles about reproducibility, both veterinary ...
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### Negative and positive AICc/BIC for two models with transformed data - how to compare?

I am using AICc for model selection for transformed data (continous variable). One model I used $\log_{10}(PWV)$ as response and the other $\log(PWV)$ as response, but I am not sure which one to use ...
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### Imputation for a zero-inflated negative binomial mixed effects model

I am working with a dataset of repeated (x4) observations on 100 subjects. The outcome is zero-inflated and the data appears to be modelled well by a mixed effects zero-inflated negative binomial ...
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My data: ...
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### Step-by-step mixed model analysis in R using lme, ezANOVA, or aov

My data consist of 4 treatments (fixed), 8 locations (2 locations per treatment), 3 positions (per location, fixed), 3 samples (per location, random), with dependent variable ...
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### Use of nlme for mixed models of repeated measures with two classifying factors and a covariate

Suppose we have a mixed model for repeated measures with response being $y$ and a covariate being $x$(say, age). There are two classification factors $a$ and $b$. Say, 5 psychological patients($a$) in ...
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### Repeated measures interaction betwen SNP and treatment with R

This is my first question is this forum. I have the a problem that I want to solve with the lme function of the nlme package of ...
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### Using lme to analyse a complete randomized block design with repeated measures: Is my model correct?

I've got a completely randomized block design with three treatments and four replications. Biodiversity was measured in four successive years. I figured that a mixed model with repeated measures as ...
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### Repeated measures: aggregate, fixed effects, or random effects?

I have a repeated measures design with data collected across 8 treatments, with 5-6 repeats for each treatment in closely spaced time intervals (time is not important in the study). I only have 4 ...
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### What is the ANOVA model to use for a 2x2 factorial experiment with units measured 3 times each?

If I were to set up an experiment examining the effects of exercise, and coffee consumption on the number of hours slept, what would the be the ANOVA model that I should use, given: 16 volunteers ...
372 views

### Mixed linear model with repeated measures in SPSS

I'm trying to run a mixed linear model analysis with SPSS. When I try to run the analysis, SPSS gives the following error message: ...
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### Linear regression with repeated measures in R

I was unable to figure out how to perform linear regression in R in for a repeated measure design. In a previous question (still unanswered) it was suggested to me to not use ...
328 views

### Split plot design with repeated measures in package (nlme) - model errors

Forgive me if this answer is already somewhere on this site, but after extensive searching I have found nothing to help me. Here is a brief overview of the experiment: I have 18 tanks, each of which ...
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### Mixed repeated measures Anova

I'm trying to assess the influence of fertilisation and irrigation on biodiversity in a complete randomized block design. I have two treatments, one control and two blocks. Treatments went on for ...
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### Analysing a balanced mixed models design?

I am designing an experiment and I'm in need of some help. Participants are presented with two videos on a website. In one period, a feature (a table of contents for the video) is enabled, while in ...
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### Questions about specifying linear mixed models in R for repeated measures data with additional nesting structure

Data Structure ...
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### How to interpret an interaction effect in SPSS output for a repeated measures anova with between and within group factors?

I have conducted a repeated measures ANOVA, with 2 factors: One between factor (Ex_control: exercise intervention versus control) One within factor (...
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### Mixed model in R with paired design and covariates

I make habitat suitability models for animal species. The purpose of my research is to investigate the accuracy of different models. I clearly have a nested design: accuracy_measure -> response ...