# ancova

1. ### ANCOVA with moderators

I am currently doing research with an independent variable (four treatment groups), a continuous dependent variables, 5 control variables, and 2 continuous moderators. I figured out that I needed to do an ANCOVA analysis with the 5 control variables as covariates and the treatment groups as...
2. ### Multiple ANCOVAs: Post hoc Bonferroni, FDR, or can I use MANCOVA?

Hi, I am comparing a protein level in multiple (40 to 4000 depending on the analysis) brain areas across three diagnostic groups, with a couple of covariates. I am using ANCOVA to compare the three groups. What is the best way to account for multiple comparisons? Where I am conducting large...
3. ### ANCOVA dilemma

Hi All, Ive been given this question: Categorise the participants into high stress and low stress groups. Compare the two groups in relation to another psychological variable while controlling for a second variable. The data i have available (which i don't need to use all) is age, gender...
4. ### Valid use of repeated measures ANCOVA?

I am running a repeated measures study with four time points. A single group of participants receive the same questionnaire at each time point, which is assessing variable X. I am determining how variable X changes over time. I plan to analyze this in SPSS using a repeated measures ANOVA (with...
5. ### Help with question: What test should I use?!

Hello. I am trying to analyse whether the weight of my patients (in 3 different treatments) has any impact on their resistance to electric current. The weight is normally distributed. I use SPSS, and I am choosing to analyse a the data using a one-way ANCOVA, since I have 1 independent...
6. ### Ancova interactions posthoc

Hi everybody, I have a rather theoretical question about post hoc test in ancova with interactions. Suppose I have situation where I analyse the impact of x on y in 3 different groups (factor: group), like in the picture below. To do stats I use R. So I run a lm( y~ x * group) than I do...
7. ### F Change Test and ANCOVA

Given R squared between the DV and covariant, R squared between the DV and treatment (two groups), R squared between DV and covariant treatment combined, and N, could you conduct an F change test? If so, how? Could you make any conclusions about the effect of the treatment?
8. ### 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...
9. ### ANCOVA - conflicting results, how to code test

I carried out a group project on a uni field course looking at whether a species' vigilance was affected by whether or not there were young in the group. We recorded the number of adults and young and then observed how much of the time the adults in each group were vigilant. We also recorded...
10. ### What type of ANOVA test should I do?

The same participants are exposed to two different screen sizes 27" (stimulus A) and screen size 9.7" (stimulus B). Independent var is "screen" with two levels - sizes. After exposure to stimulus A, they fill two questionnaires to answer dependent variables Y1 and Y2. After that, they are...
11. ### split-split plot with continuous subplot variable

Hello I am trying to analyze data from a split-split-plot design. The sub-plot is a continuous factor and since we suspect a non-linear relationship, the quadratic form needs to be tested as well. Factors: a-main plot-5 levels b-subplot-continuous c-sub-subplot-2 levels. To test the quadratic...
12. ### Multi-level modeling?

I've spent the last two days reading and attempting to find an answer to my question but I am unsure if the answers that I am finding are even accurate because to be honest, I am not sure what to call the analysis that I am attempting to use. I am using SPSS for analysis procedures, so any help...
13. ### simultaneous confidence interval for difference between slopes in ANCOVA

I am new to the forum and R. I am using R version 3.2.0 on Windows7. I am trying to find the simultaneous confidence interval of pairwise difference between slopes. In my data, there are three variables - Y, X and group. I am trying to find CI of difference between slopes for all the...
14. ### 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...
15. ### Reasons and advantages of using an ANCOVA instead of a Regression

Hello everyone, Just wondering if any of you could help me. Just wondering when the variables I’m using can be used for both ANCOVA and regression, what would be the advantages of using an ANCOVA? The way I’m using it is that the impact of the variable of interest is being examined by...
16. ### Need help to choose right statistical analysis

Dear all, I have one dependent variable (Y) and 3 independent variables (X1, X2, X3). All dependent and independent variables are continuous. I want to know which independent variable (X1 or X2 or X3) is a predictor of the dependent variable. If they all are, whether they are independent...
17. ### Choosing Appropriate Statistical Analysis: ANOVA vs ANCOVA

Dear all, I have one dependent variable (Y) and 3 independent variables (X1, X2, X3). All dependent and independent variables are continuous. I want to know which independent variable (X1 or X2 or X3) is a predictor of the dependent variable. If they all are, whether they are independent...
18. ### ANCOVA assmptions not met.

Hi, What is the non parametric alternative for parametric ANCOVA if we find that some ANCOVA assumptions are not met? How it can be done in SAS?
19. ### Pre and Post with Treatment group - ANOVA , ANCOVA, Regress differences???

Hello friends, My main task is to "test" if staff member who participated in the counseling sessions had fewer "Use of Force (UOF)" incidents in the 6 moths after the counseling session. I have a data set with the number of UOF incidents for the staff member in the 6 months before (pre) and...
20. ### Shapiro-Wilks significant, all other indicators NORMAL

Hello everyone, I am checking my assumptions before running an ANCOVA, one of which is that the DV is normally distributed across all levels of the IV. MY IV is 3 groups (Ns of 32, 31, and 32) and my DV is a continuous variable from 1 - 5. Before splitting into groups, it looks normal and the...