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 use a linear model with two factors and repeated measures?

Suppose I have a date set of the form: ...
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dependent and independent categorical variable across eight trials

Study: significantly selected color for a particular letter. My sample size is 30 and the study is within subject. Independent variable -> letters (total 8)... Dependent variable -> colors ( total ...
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21 views

Repeated measures linear mixed effects model

I am working with trees that were fertilized in a full factorial design (N x P x K) in plots that are replicated four times. I currently have a mixed effects model with this structure: ...
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1answer
18 views

SPSS - Calculation of confidence intervals in estimated marginal means of repeated measures ANOVA

I used SPSS to do a repeated measures ANOVA including one within- and one between subject factor. Let's say the between-subject factor is treatment group with levels treatment and control, and the ...
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31 views

Difference between two measures

A numerical value was generated for each of 65 samples on machine A at time T, and then on machine B and time S. I tested for a difference between the two runs using R as follows: ...
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GEE as alternative for Linear Mixed Models

A linear mixed model requires the residuals to be normal. In the case of a simple linear mixed model with a random intercept only, a colleague of mine was arguiing that I could just use a GEE with an ...
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19 views

How to account for both between-subjects and within-subjects covariables?

I have a data set I'm trying to analyze and I can't figure out how to include the two different kinds of covariables in my analysis. Without the covariables, the analysis isn't too complicated. It's ...
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6 views

Specifying interaction contrasts for within x between terms in SPSS

I am trying to analyse a dataset with 3 groups of subjects and one repeated measure with 6 levels (accuracy at identifying 6 different emotions). I am using the GLM command from SPSS to do this, which ...
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20 views

Logistic regression with multiple outcomes

I have a study looking at the association between a novel diagnostic measure (continuous var) and a health outcome (measured at 4 different time periods; binary). In addition, data on traditional ...
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6 views

Repeated measures in GLMM

I have a dataset in which individuals in some plant populations were measured over 3 consecutive years. My response variable is the reproduction of each individual. My fixed effects involve: one ...
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13 views

How to specify repeated-measures model most adequately and correct for multiple comparisons

I am struggling with 1) the correct specification of my model and 2) the question on how to correct for multiple comparisons. The details: I have a data set from 13 subjects, measured on two ...
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26 views

Compare means of two (contentwise) different variables

I have a question about comparing the means of two variables that have a different meaning but a (possibly) similar ways of measuring them. To give an example: Let's say I am conducting a study in ...
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58 views

Should the within-subject variability decrease?

I have a crossover experiment design, detailed as follows. there are 7 sites conducting the same experiment; In the experiment of each sites, 5 different treatments are administered to $n_i, \, (i = ...
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27 views

Adding in L2 predictor in GLiMM fails even though ICC is high

I'm using SPSS GLiMM to run a repeated measures logistic regression model. Research Qn I'm interested to know if a MP is more likely to make a particular response (e.g., apology, challenge, denial) ...
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20 views

Help need identifying analyses methods

Any and all help would be much appreciated! I've detailed a bit of information below, but if I left anything out please let me know My hypotheses are (info: NA= novel asssembly; S= selections or ...
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15 views

MANOVA on long data format

I need to run repeated measures MANOVA on long data format (the format was created to derive a categorical variable that is needed to be used as IV). Running RM MANOVA on long data format using a ...
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181 views

R: equivalence between an aov between-within repeated measures model and an lmer mixed model

I have some trouble obtaining equivalent results between an aov between-within repeated measures model and an lmer mixed model. ...
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Estimating and comparing pre-post treatment effects in multiple pairs of treatment-vs-control groups

I have a dataset from an experiment where the goal was to study in which plant ecotype a treatment with a certain bacteria had the greatest effect. Hence the data consists of a number of control and ...
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24 views

How to analyse binary outcome data with between- and within subjects factors?

I am looking for the right statistical procedure to analyse my data (mixed design) with binary outcomes. Between-subjects variable: treatment (yes or no); experimentally manipulated Within-subjects ...
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14 views

F-Test in ANOVA with two within-Factors: why are there different denominators in the F-test?

in a two factorial ANOVA, the MS of Factor A (or B) as well as the interaction is divided by the MS of the residuals: e.g. F = MS_FactorA/MS_Residuals If I have two within factors, only the ...
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Pretest-Posttest comparison

I am having a hard time doing this on Stata. I have a group of 32 students. All perform a pretest and are scored. Next, half of them are randomized to receiving an intervention and the other half ...
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39 views

Repeated measures ANOVA and uneven number of trials

Suppose I have multiple responses from each subject in three different conditions (A, B, C). If I would decide to run a repeated measures ANOVA, I would first average over the repetitions from each ...
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Using Factor Analysis prior to repeated measures ANOVA

Please note, stats is NOT my area (hence why I need help!) and I may not be using the correct terminology. I hope I can explain my question clearly enough. BACKGROUND: I have collected behavioural ...
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24 views

Assumptions for nlme

I want to analyze a repeated measure design with two independent variables (var1, var2) where the subjects had to solve three ...
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36 views

Which statistical test to use with repeated measures & clustered observations?

I am doing an experimental study for my research. I have a class with 24 students and six groups, where each group includes 4 students. I want to compare the performance of each group in two cases: ...
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Statistical test for repeated measures ANOVA with covariates

We have 10 participants who have undergone a cold pressor test (for pain) in 3 conditions (no drug, drug A, drug B). It is a repeated measure design. The stimulus is continued for 1 minute after they ...
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33 views

How to cluster data with repeated measurements?

Most clustering algorithms assume that data points in each row are independent. I have some data with repeated measurements from individuals. I can use a standard algorithm, and then check to see if ...
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Variance of difference of $x_{i,t}$ and $x_{i,t+1}$

We have $n$ observations of human performance before and after a training program. We have a random sample of $n$ individuals and assume population distributions are normal. We thus have: $x_{1,t},\ ...
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G and R matrices in mixed model and model selection

I have data in which the plants were subjected to four conditions and measured weekly for a month. I would like to incorporate "plot" as a random factor into my linear mixed model using SPSS. I am ...
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Analysis of a longitudinal study where interventions are received at different time points

I have a data set of university students. The university has 8 different assisting programs, mostly like scholarships, for needy students to help them concentrate on their studies. Since it costs a ...
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1answer
85 views

One observation per level in mixed-effect model

Field explains how to analyse repeated-measures data using linear mixed-effect models (LME). See Field et al., Discovering Statistics Using R, 2012, p. 573. However, the way he specifies the model, ...
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49 views

Measuring longitudinal data where individuals have missing observations

We have a longitudinal panel of X users with their online spending patterns and are trying to measure certain metrics within the panel. We have time series information about the users such as their ...
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1answer
43 views

How to test for differences among 3 treatments pre & post, all within subjects?

I want to compare the changes in blood pressure occurring following 2 anesthetic drugs. So in a crossover design, each participant comes for 3 sessions and gets either of placebo, drug A or drug B on ...
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30 views

How to determine which covariates to use

This may seem like a basic question but here goes... I am looking at the effect of brain stimulation on skill acquisition across several timepoints. I have several measures that may be useful as ...
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39 views

Few principles of linear regression

I have had hard time to find definite answer to following theoretical issue: Lets say I have data which has 20 subjects and same blood level measurement (repeated measurements) has been assessed in ...
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97 views

Summarizing and plotting several combined relationships with LMER

I want to see if there is a significant relationship between predictor and value. I've measured these two variables in 6 different conditions (not a full 3 x 3 design because feature1 and feature2 ...
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Interpreting an interaction in the presence of main effects

I'm having a crisis of confidence in my stats and I was wondering if somebody could help me. I ran a 2 x 2 x 2 x 3 repeated measures ANOVA and got: 2 main effects 3 2 x 2 interactions and a 3 way ...
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16 views

Longitudinal design: how to take into account baseline measures

I have a (small) data set of 15 subjects randomly assigned to one of two groups. All subjects were measured at 7 time points. Ideally, I would like to answer if the groups differ at certain time ...
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1answer
30 views

Why does my repeated measures ANOVA analysis vary when I organize my data differently?

In my study there were 63 types of stimuli (63 levels of the IV) and all types had 8 different examples (8 trials per level of IV) which were all categorized by each participant. Accuracy of ...
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4-way Repeated Measures ANOVA

exchangers! I am struggling with my data analysis for an article I'm writing. I have to following experimental set-up. Instruction (A/B) Group (Alcohol Dependent / healthy Control) - between ...
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1answer
38 views

1-Way ANOVA with single independent/repeated (within/between) factor

I want to perform an ANOVA on data with a single factor with three levels. The difficulty for me is that two of the levels are repeated measures (within subjects) and the third level is independent ...
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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: ...
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Two repeated measures treatment analysis. Regression of the delta or mixed effect model?

We want to study the effect of a certain treatment on performance on a test and I would like to have some suggestion from you. We want to use a regression model in order to control for confounders. ...
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30 views

Discrete Variables and Regression

I have only discrete independent variables (gender, religious affiliation etc) and continuous dependent variables. Is it possible to use a regression model?
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Moderated regression in repeated measures

I recently conducted a study with 4 within-subject conditions, divided over two sessions. My independent variable is degree of emotional eating (as measured by food intake after a negative mood ...
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41 views

How to report confidence intervals for an interaction?

I have a significant interaction in a repeated measures ANOVA. Two groups in my data are significantly different from one another. In order to report the overall confidence intervals, when I report ...
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24 views

Joint model for ordinal repeated measures data and MNAR dropout using R

I have a dataset consisting of repeated measures data of graded toxicity scores (0-4) in a large number of patients being treated with a anti-cancer drug. We would like to identify predictors for ...
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1answer
116 views

I just don't get the t-test

I know it sounds abysmally ignorant, but here we go. I understand the basic logic behind the t-test: you want to know whether the difference in the mean of two samples is due to chance or not. To ...
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44 views

Linear Regression with repeated measurements of replicate samples?

This is a simple question but I has bugged me for some time. Can someone please share a link, or describe, how I can perform a linear regression from repeated measures of replicate samples over a ...
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35 views

Two-way Repeated Measures ANOVA with replicated measures

My experiment involves 16 participants with a dependent variable (PP) tested under 2 conditions, across 3 different time-points. At every time-point, each participant is tested twice. My data is ...