# Tagged Questions

Repeated measures data occurs when more than one measurement is collected on the same unit (e.g. subject). This data cannot be analysed through normal methods because the rows in the data are not independent due to the multiple measurements. The time sequencing of the measures may not be important.

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### How to analyse repeated measure ANOVA with three or more conditions presented in randomised order?

Context: My question concerns a typical design in my area – a researcher takes a group of subjects (say 10) and then applies three different conditions to them to measure the change in a response ...
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### simple repeated measures syntax - lme vs. lmer

I'm trying to look for significant effects on "similarity" (of "isinpair" and controlling for time effects) using repeated measures with an in group sample. The intervention "isinpair" occurs after a ...
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### Balanced repeated measures design

Okay this is my problem: I have 12 participants. Each participant spent 3 nights in my lab doing a reaction time task at four timepoints during the night(12, 1, 2 and 3 oclock), with one week ...
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### How to use G Power 3 to calculate statistical power in mixed design ANOVA with unequal group sample sizes

In G power 3, ANOVA repeated measures within-between interaction: Only the total sample size is reported assuming equal sample size for the two groups. My questions are: How would it work if the ...
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### How to compute confidence interval in ANOVA with repeated measures?

I made a model using repeated measures univariate ANOVA in R. ...
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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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### Friedman test to report on occurrence of categories in multiple articles

To investigate reasons for certain behavior, we have defined three categories for these reasons, and have determined how often these were mentioned across 15 (very different) scientific articles. ...
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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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### 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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### Effect size measure for doubly-repeated measures design?

Update: I haven't gotten any answers, so I am simplifying my question. Say I measure test scores of $100$ people in one of two conditions. Each test has $10$ items. On each item, each person can ...
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### Is repeated measures ANOVA appropriate for my experiment and is my sample size large enough?

I'm really confused. I never took statistics but am trying to read up as much as I can. I didn't think much about statistical analysis until after doing the experiment, unfortunately, but maybe ...
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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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### Significance test for categorical repeated measure data

Despite my best search, I wasn't able to find any solid leads for my problem, so I thought I would share it with the community. It's a question about how to detect a difference between multiple ...
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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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### Repeated comparisons over time between two groups

I have to compare the mean between two groups over time. The difficulty here is that I have to make this coparison about 80 times. And it is not enough to know whether there is a difference, but I ...
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### Linear Discriminant Analysis: Using subject as classification

I have a problem where I need to identify from which subject a particular set of data points came. More specifically, my problem is that I need to demonstrate that my subjects (N=9) can be ...
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### Mixed-effects for repeated measures in Matlab — how to choose a model?

This post follows on from this one. I am trying to analyse a dataset: $S$ subjects were tested for $A$ measures in $B\times C$ conditions. I have worked out that I can perform a repeated measures ...
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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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### Multilevel modeling of experimental data with repeated measures in the same condition of factorial experiment

I'm struggling with modeling some experimental data using the lme4 package in R, and would appreciate input. My experimental design is as follows: subjects ...
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### Pretest-posttest plus control design

I am evaluating the effect of an intervention (treatment: a lecture) on the ability to spot behavioral clues of emotions using visual stimuli using pretest-posttest plus control group experimental ...
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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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### Specification of error terms in aov() in R

For a two-way repeated measures design, we can specify the model using aov in the following fashion: ...
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### How to test proportions of a Categorical response variable for a Repeated measures design with Unequal Sample Size?

I have a question about the analysis of a unequal sample size repeated measures data with categorical response variable. This experiment looks at 5 young and aged persons and for each of the ...
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My data: ...
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### Best practice when analysing placebo-controlled within-subject designs (cross-over trial)

I would like to analyse data from a placebo-controlled within-subject design. For every subject a numeric outcome variable (Y) was measured twice - once following administration of a drug and once ...
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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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### How do I estimate a repeated measures ANCOVA in R and SPSS?

I'm currently running a perception experiment: DV: error (this in degrees- how much an observer was away from the real answer) IV: the time bin (5 levels) in which the unique stimulus appeared ...
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### How to tell if a continuous variable is associated with (treatment) change in another variable over time (one group, time 1, time 2)?

Hypothetical: I have treated a sample for depression and have (continuous) depression scores at intake (Y1) and at the end of treatment (Y2). I am wondering if motivation (X) at the start of therapy ...
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### How to test for differences in binary score data?

I have data from a human subject study that was setup as a 3x2 (system by task type) experiment, with 24 participants. Each participant completed 6 tasks in all, one using each of the 3 systems, and 2 ...
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### How can I compute a repeated measurement ANOVA with a mixed model?

It is my task to program a mixed model. The data is from 20 experimental subjects, who were measured under 2 factors. Factor A has 7 levels, factor B has 3 levels. So, that for every subject I got 21 ...
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### How do I fit a nonlinear mixed effects model for repeated measures data using nlmer()?

I am trying to analyze repeated measures data and am struggling to make it work in R. My data is essentially the following, I have two treatment groups. Every ...
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### Mixed model with repeated measures and both of two treatments with lme or lmer in R

I know just enough about lme() and lmer() to get myself by with simple models, and to get myself into trouble with more complex ...
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### How do I derive principal components taking account of repeated measures?

I have data from a 24-item (each item ordinal) scale used at two time points in 2 groups - before and after treatment with treatment A and treatment B. I want to capture a core group of symptoms that ...
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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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### Which model for data which has within-effects, between effects and non-parallel lines

My data (Panel, 19 countries, 7 years, ordinal outcome variable) has within-effects (countries over time), between effects (between countries) and it seems as if the slope of lines (test of parallel ...
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### One factor repeated measures where first time point is a control

Patients were randomized to two groups (control and intervention). Each patient is evaluated at 3 time points. The first time point is taken pre-intervention, so it should have the same mean response ...
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### Violation of Normality in Mixed Design ANOVA

I conducted a study in which two groups of teachers (pre-service and veteran) all watched four video clips of instances of aggression between students. The clips differed by type of aggression and ...
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### Interpreting Two-way repeated measures ANOVA results: Post-hoc tests allowed without significant interaction?

I have conducted a study where I employed a two-way repeated measures design to investigate whether subjects respond to a main treatment effect. What I'm mainly interested in is whether subjects ...
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### How do I compare stimulation levels between different stimulants with time points?

I have collected data that represent stimulation levels in three different time points ($T_0$, $T_1$ and $T_2$) using three different stimulants ($S_1$, $S_2$ and $S_3$) and a control ($C$). I have ...
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### If I compare conditions within two preexisting groups is that a quasi-experimental design?

I have two groups of participants, one group of psychosis patients and one group of controls. All of the participants complete a computer task that has three different conditions. So, I want to make ...
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### Analysis of repeated measures when fixed effect changes within-subjects?

I'm helping a colleague with a repeated-measures analysis in which each subject's fixed effect changes over the course of data collection. He's measuring a continuous, positive response variable ...
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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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### Should I run measurement invariance if confirmatory factor analysis is not affirmative?

I have a repeated measures design for a Likert scale with 10 items. This scale is assumed to be unidimensional and this is one of the research questions along with the scales measurement invariance ...
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### Which repeated measure statistical test must I use in this case?

I have a set of general conditions A, B, C, D, E and F to solve a problem. Each of these conditions lead me to different number of experiments according to a parameter that i change in each general ...
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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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### How to test difference between two items rated on a Likert scale by same participants?

I have conducted a survey with multiple 5 point Likert scale questions ranging from 1 = very unimportant to 5 = very important. I used frequency distributions, and stacked bar charts to show which ...
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### Repeated measures ANOVA in R for non-orthogonal design

I have data from a two-factor within-subjects experiment design where the conditions are not orthogonal. Factor one (Location) has three levels; factor two (Stimulus) has three levels, one of which is ...
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### Two uneven groups (101 vs 21) measured twice; what repeated measures ANOVA equivalent can help?

I have a question that I have difficulties in answering: I have two groups of patients tested twice at the same continuous variable. Group A=104 & GroupB=21. So two groups, one continuous ...