Tagged Questions

33 views

Interpretation of intercept in Helmert coding

I have a general, presumably simple, question, but I couldn't find a conclusive answer so far. Assume I have a simple case of a General Linear Model with one categorical predictor variable, that has ...
17 views

Contrasts for one factor in a repeated-measures ANOVA

I am trying to set custom orthogonal contrasts for a repeated-measures design using R. Is it possible to set contrasts just for one factor? The model looks like this: ...
29 views

One factor repeated measures where first time point is a control

Patients were randomized to two groups (control and intervention). Each patient is evaluated at 3 time points. The first time point is taken pre-intervention, so it should have the same mean response ...
52 views

Non-Orthogonal Planned Comparison: How to correct for alpha?

I have a data set containing three groups (A, B, C). Group A and Group B have undergone two different types of training designed to improve the same thing. Group C is my control group with no ...
103 views

Defining contrasts in ANOVA to compare mean differences

I would like to run an analysis of variance (parametric or not) with two factors; each factor having two levels. So if x, y is are the levels of the first factor and 1, 2 the levels of the second I ...
42 views

How to Partition An Interaction SS in ANOVA

I'm a new user of R and I'm trying to replicate Table 6.18 on page 262 in Statistical Procedures in Agricultural Research, By K. A. Gomez and A. A. Gomez. New York, Chichester, etc.: Wiley (1984). ...
53 views

How to avoid regression to the mean in a simple comparison

This is a pretty simple question but I haven't been able to find a clear answer to it. I have some data from a behavioral experiment taken under two conditions (A and B); within each condition, each ...
187 views

Checking confidence intervals on user defined contrast (one-way ANOVA)

Hi is anyone able to help - I am doing this all in R Code: I have run one way analysis on some data and set up 2 contrasts (Liberarts-Finearts and also Engineering-science). I now need to calculate ...
576 views

Effect size in contrast analysis

I'm running 2-way repeated measures ANOVA (3 and 5 levels) with planned contrasts afterwards. I'm interested in comparing 1)levels of the first factor among themselves (e.g. A1B with A2B, A2B with ...
304 views

Orthogonal contrasts in R

I am having somewhat of a problem setting up contrasts from an anova in R. I have done this in the past, but at the moment I don't seem to be able to get R to use my contrast matrix instead of the ...
450 views

Contrasts in repeated mesures ANOVA in R

I am a refugee from SPSS in the process of re-learning how to do everything in R. Mostly it's been fun, as R is great for a lot of things but I've run into a snag that I can't seem to find a solution ...
499 views

How to define contrast coefficient matrix?

I have this data ...
426 views

How to interpret these custom contrasts?

I am doing a one way ANOVA (per species) with custom contrasts. ...
227 views

Refugee from SPSS having issues with fit.contrast in R

I'm trying to wean myself off of SPSS and switch to R for psych statistics and I'm mostly getting there, but I've run into a real roadblock with fit.contrast from ...
162 views

How to test and examine interaction effect in 2 by 3 by 6 mixed ANOVA design?

Background: I have two groups of children - one group with normal hearing and one with permanent hearing losses - call them NH and PHL. Each child has had a hearing test, consisting of 6 different ...
4k views

What if an overall ANOVA is not significant, but specific contrasts are?

Study Design: I have a 2x3 factorial design, 2 levels of Time (2050 or 2100) by 3 levels of information (None/Control, Moderate, Extreme). I set up some very specific contrasts when analyzing this ...
320 views

Contrast to ANOVA with interaction term

I need to fit orthogonal contrasts to the following model. The following example data. ...
1k views

How to perform a 4 by 4 mixed ANOVA with between- and within-subjects contrasts using R?

Beginner user of R here struggling with a repeated measures ANOVA. I have a dataset that consists of one between subjects factor with 4 levels (coded in a single variable called 'groups'), and one ...
2k views

How to specify specific contrasts for repeated measures ANOVA using car?

I am trying to run a repeated measures Anova in R followed by some specific contrasts on that dataset. I think the correct approach would be to use Anova() from the ...
384 views

Are linearly dependent contrasts permitted when performing planned comparisons in within-subjects ANOVA?

Here it says that planned comparisons should be linearly independent. Here (page 13) and elsewhere I see people giving examples of linearly dependent contrasts. How should this conflicting advice ...
6k views

Post hoc test after ANOVA with repeated measures using R

I have performed a repeated measures ANOVA in R, as follows: aov_velocity = aov(Velocity ~ Material + Error(Subject/(Material)), data=scrd) summary(aov_velocity) ...