# covariate

1. ### Effect of larger variance in covariate (or: getting closer to a normal distribution) on result of ANCOVA

Hello, I have a question about ANCOVA. We did an experiment with 2 groups and then calculated an ANCOVA to see if the DV differed between the groups. We included one binary and one continous covariate (PO). Both did not sig. differ between groups. It was criticized that PO is skewed - we...
2. ### Control variables in mediation analysis?

Hi, I want to conduct a mediation analysis, which will investigate whether the change in depressive symptoms during treatment (time) is mediated by the change in OCD symptoms. Currently, I have time as my predictor, OCD symptoms as my mediator and depressive symptoms (at time t+1) as my...
3. ### Which test to use?

I have to analyze a within-subject experiment with a continuous dependent variable and a categorical dependent variable (brain stimulation: Anode, Cathode, Sham, performed in different sessions separated by 48 hours). Although the order of stimulation (e.g., Sham first, Anode second, Cathode...
4. ### Repeated Measures model with Covariates

Hi Everyone, i am struggling with finding a good way to analyze a dataset. The design is this: I have 25(n) subjects, all of them are tested in an experiment under 9 conditions. I estimate an electrophysiological index (idx) in every condition for each subject. Now I want to ask whether the...
5. ### Welch ANOVA and covariates

I had planned, because of lack of homogeneity of variance for some of my variables (homoscedasticity) to run a Welch's ANOVA and to use bootstrapping. I also have a number of covariates proposed for the (original) analysis. The Welch's ANOVA is only available for one-way ANOVA's on SPSS (no...
6. ### Decomposing a mixed model custom ANCOVA

Here is my scenario. The first paragraph tells a bit about the methods we used to give you a frame of reference. The second tells about the first analysis and the third about the second. I can provide more details if anyone thinks it could help. I recently collected data for a study about how...
7. ### R mlogit: How do I interpret marginal effects using absolute or relative type?

Hi R users, I use effects() to compute the marginal effects of a mlogit model in R. effects(object, covariate = NULL, type = c("aa", "ar", "rr", "ra"), data = NULL,...) Which type ("rr", "aa", "ar", "ra") in effects() should I use when estimating the marginal effects? How do I...
8. ### repeated measure ancova

Hi, I do have a rather simple question but could not find a direct answer on other forums. I ran a repeated measures ancova with time (2) as within-subjects factor on accuracy rates (so that one was measurd twice) and entered age as the covariate. in the between-subjects table the...
9. ### Mixed ANOVA with covariate - interpretation help!!!

Hi, I conducted the following mixed ANOVA with a covariate: 2 x groups (BS factor) 3 x Switching as repeated measures (WS factor) IQ as covariate. My output gave me the following results: in the BS-table, the effect of IQ and group x IQ was not significant. Which is good, I guess. not so...
10. ### Need design help...not sure how to analyze

Hi, I am writing a proposal in which I am trying to implicitly activate a stereotype. Specifically, I want to see if professional sexy attire (not revealing...i.e., knee length pencil skirt, collared shirt, fitted blazer) will activate the "business woman" stereotype or the "sexy woman"...
11. ### Analysis for a repeated measures design with covariate that varies over conditions?

Hi all, I'm trying to find the correct analysis that will allow me to carry out the equivalent of a repeated measures MANCOVA with a covariate that varies over three conditions. Basically I have an experiment with 3 different types of task where every participant does every task in a...
12. ### Which approach to use? Repeated measures with a covariate

Hi, I hope that someone can give me a pointer please. I am trying to determine which is the most appropriate test to apply to my data. I have some data which were originally formulated for a 2x2 Repeated Measures ANOVA. I was particularly interested in the A*B interaction. However, having...
13. ### Assumptions in ANCOVA, and consequences of violating them

I ran an ANOVA with 4 predictors (2 categorical, 2 continuous) and 1 covariate (continuous). Including the covariate did not significantly alter the main effects of the ANOVA when it was run without the covariate, so I concluded that the covariate did not need to be included in the overall...
14. ### repeated measures ANOVA with covariate

Hello everyone, just one quick question. I'm sure somebody knows how to do this. I conducted a repeated measures ANOVA and added a continuous covariate. Now there is a significant main effect of that continuous covariate. If I report that main effect I need to say something about its...
15. ### Date as a Covariate

Hi, I am looking at the effect of various weather variables on sub-population size of a certain species of snake. Sub-population size at the study site over the active period follows a quadratic shape increasing in the spring to a peak in the summer and drops in the fall. Temperature during that...
16. ### Repeated measures ANOVA w/ time-varying covariate that does not vary across subjects

Hello community: I am seeking assistance with a repeated measures ANOVA. In this experiment, I examined the return rate of bees to colonies (= dependent variable). These colonies were subjected to one of four food treatments (= categorical predictor variable). The return rate of bees was...
17. ### Statictical suggestion regarding DOE and GLM for the pharmacutical related problem

We performed a DOE to study the relationship between simulated intestinal fluid (SIF) components and solubility of drugs. The DOE is composed of 7 factors (representing the components of SIF) and 2 levels for each drug. And we have done several drugs with the DOE. Now with the DOE analysis, we...