Tagged Questions

2
votes
1answer
71 views

Why is ANOVA interaction no longer significant after including a covariate?

I have initially run a 2x2x2 Anova and found some significant interaction between the independent variables. I then ran a ANCOVA where I added a covariate. I am confused with how to interpret the ...
0
votes
0answers
67 views

Interpretation of interaction effects for ANCOVA in SPSS

I am now evaluating the results of my experiment on what influences the likelihood of installing a specific application (continuous variable). I manipulated 2 factors: reputation of a provider of the ...
0
votes
0answers
85 views

ANCOVA (GLM) versus Mixed Linear Model with covariate measured at both pre- and post-treatment (in SPSS)

I'm trying to analyze a pre/post study with 4 treatment groups. The Dependent Variable, Speed, measures how quickly a person's facial expression reaches peak intensity; this measure is normally ...
0
votes
1answer
98 views

SPSS:While performing ANCOVA, I get a warning: large number of columns may cause integer overflow. How do I resolve this?

SPSS Warning The large number of columns in the design matrix will cause integer overflow. The large number of columns may be due to too many levels in one or more factors, or to higher-order ...
0
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0answers
66 views

Two-way Ancova in SPSS

Does anybody know the syntax to do an ANCOVA with two IV and one covariate in SPSS? Best, Nuria
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 ...
1
vote
1answer
163 views

How to specify ANCOVA interactions in SPSS?

I'm trying to run ANCOVA in SPSS, with a continuous IV as well as a continuous covariate. Variable Information: 1 DV: Continuous 2 IVs: 1 Continuous and 1 Categorical 1 Covariate: Continuous I ...
0
votes
0answers
119 views

How do I test the assumptions of a independent two-way ANCOVA with SPSS?

I really need help in testing these assumptions regarding a two-way ANCOVA with SPSS: Independent variables orthogonal to the covariates Covariates must have a homogeneity of regression (or ...
4
votes
1answer
199 views

Different ANCOVA results in R using different functions

before my actual ANCOVA I would like to test whether there is a significant interaction between the IV and the CV as this is one assumption for ANCOVA. I found 3 different ways in R to perform an ...
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 ...
2
votes
1answer
100 views

How to determine if a change in F value when introducing a covariate, is significant?

My question may be very basic but I hope that you can help me. I have got two groups (A and B). I am measuring two continuous biological measures (X and Y) which are significantly positively ...
2
votes
3answers
534 views

How to get rid of heterogeneity of regression slopes using multilevel modeling?

I have problem with homogeneity of regression slopes in ANCOVA. I have two species of snakes and I want to compare their tail lengths (dependent variable), that are dependent on body length (in ANCOVA ...
1
vote
2answers
2k views

Significant interaction between covariate and factor in SPSS GLM

In testing gender difference on the relationship between variable A and B, A is the covariate (or independent variable) B is the dependent variable Gender is the factor As I understand it, if ...
0
votes
2answers
1k views

General linear model with interaction term in SPSS

Following my question here, I will be most grateful for further assistance to clear my confusion. The confusion is because I have read in many places that when you use ANCOVA in GLM (in SPSS), the ...
1
vote
0answers
323 views

Fitting generalized linear model with covariate

In our experimental design, we are assessing the effect of TMS on decision making. Our data is not normally distributed because our assesment test results in mean count data (ultimatum game). Besides, ...
4
votes
2answers
449 views

Longitudinal relationship between chocolate consumption and happiness: repeated measures ANOVA?

I am using SPSS and having some trouble with a research question which is analogous to the hypothetical question: Is there a longitudinal Relationship between Happiness and Chocolate Consumption? ...
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: ...
4
votes
2answers
2k views

Checking factor / covariate independence in ANCOVA

One of the ANCOVA assumptions, as I read it here, says that: Independent variables orthogonal to covariates. In traditional ANCOVA, the independents area assumed to be orthogonal to the factors. If ...