Tagged Questions

2
votes
0answers
61 views

mixed ancova or difference scores?

I am puzzled with how I should analyze the following data: The dependent variable is respiratory sinus arrhythmia, a measure of parasympathetic activity (RSA). I have a $5\times5$ full factorial ...
0
votes
1answer
138 views

Comparing means - 2 repeated measures variables, controlling for covariate with heterogeneous slope

I have a 2 level repeated measures DV of accuracy, and a covariate of response bias. As response bias increases, accuracy level 1 increases while level 2 decreases. I want to see if there is a ...
3
votes
0answers
368 views

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 ...
1
vote
1answer
245 views

Interactions with R? ANCOVA in R? I want to see if certain variables affect a dependent variable in R using repeated-measures

I have done an experiment in which the same people have been measured in two conditions, the same room with and without plants. I know they performed significantly better on a reverse digit span task ...
3
votes
0answers
129 views

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 ...
2
votes
0answers
120 views

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 ...
0
votes
0answers
128 views

Interpreting repeated measures ANCOVA in R

I am new to R and trying an analysis that I can't figure out how to do in JMP. I incubated wood samples in various stages of decay at four different temperatures and measured respiration rate and ...
2
votes
1answer
102 views

How to control for depression when sample was measured using two different tests?

I am looking at pre and post test depression scores in a 2x3 design with treatment and genotype as the IVs and depression score as the DV. However, I have to use one depression test for younger ...
5
votes
1answer
1k views

Repeated-measures ANCOVA in R?

experts, I would like to ask for advice regarding the analysis of a dataset I am currently working on. In the experiment subjects were tested in a reaction time task (RT as dependent variable). In ...
1
vote
3answers
2k views

ANCOVA or repeated measures ANOVA?

I have 3 groups randomised to intervention A or B or control. Participants were measured pre and post intervention - should I use repeated measures ANOVA or ANCOVA with the variable measure at time 1 ...
1
vote
0answers
260 views

How to perform ANCOVA on mixed experimental design where covariate is one level of a condition using R?

This is a second question related to previous post: Is this mixed ANOVA correctly specified in R? To reiterate, the setup is as follows: Groups: two groups of 8 subjects (16 total) Two conditions: ...
1
vote
0answers
731 views

How to perform non-parametric ANCOVA adjusting for differences in age and sex?

Context: This is the design: 11 patients were examined for a "Response Parameter" before and after a specific treatment. 12 healthy control patients were examined for the "Response Parameter" (did ...
2
votes
1answer
107 views

Assessing effect of intervention where aptitude tests used in pretest and posttest have some overlapping and some distinct items

In my research there is a pretest, and a treatment followed by a posttest. The pre and the posttests are similar but not exactly the same. A few questions were changed between the pre and posttests ...
2
votes
2answers
466 views

ANCOVA with multiple instances of the between-subject covariate

If I find that my covariate (reaction time) alters over the length of my experiment (e.g. due to fatigue), can I somehow build that into my model? So what I am saying is that the effect of my ...
1
vote
2answers
3k views

How to set up a two-way mixed ANOVA with a covariate in SPSS?

I wanted to carry out a two-way ANCOVA for my data. However, SPSS isn't liking that I have only one IV. I have One IV: Group (3 levels, i.e. 2 experimental groups and a control group), One DV: ...