Tagged Questions

1
vote
0answers
13 views

Are the sequential sum of squares appropriate when treatments must be applied in sequence?

I'm working with some modeled future stream flow data that was created in two steps. First, future precipitation predictions (at certain points in a watershed) were created by running historical ...
1
vote
0answers
23 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). ...
6
votes
0answers
132 views

Type III sums of squares

I have a linear regression model with one categorical variable $A$ (male & female) and one continuous variable $B$. I set up contrasts codes in R with ...
4
votes
1answer
176 views

R, Differences between lm and aov

What does explain the differences in p.values in the following aov and lm ? Is the difference only due to different types of Sum of square calculations ? ...
1
vote
0answers
62 views

Type I ANOVA tests not depending on the order of the factors

I have a dataset with two factors A and B and the following design (contigency table showing the number of individuals for each ...
1
vote
0answers
56 views

Different Mean Square partitions in an unbalanced bifactorial ANOVA (with random factor) between R and Statistica

I am trying to extract variance components for selection and chance in a bifactorial design with Generation as a fixed factor and Replicate as a random term, for early fecundity. Since I am using ...
3
votes
0answers
182 views

Missing cells with Type III SS

I have a linear model of the form y ~ x + z + x:z. I have unbalanced data and further have a few missing cells (data would be unbalanced even without those missing cells). My understanding of the ...
2
votes
1answer
98 views

Proper order of variables in unbalanced ANOVA

If you have unequal sample sizes in cells, then the order in which you enter model terms changes your results for sequential or Type I SS. The first variable to enter the model is allocated its ...
3
votes
1answer
419 views

Using and interpreting type I SOS in three-way ANOVA

My research question is from education: To test whether groups (university, department, gender) differ based on their scores in a test, and whether there are any interaction effects, I'll do 3-way ...
3
votes
1answer
556 views

Analysis of variance table for 2x2 cross-over trials

I am trying to reproduce the anova table for a 2x2 cross-over design. I used the data listed in tables 2.1 and 2.2 of the "Design and Analysis of cross-over trials" book, by Jones and Kenward. I am ...
4
votes
1answer
2k views

How to interpret type I (sequential) ANOVA and MANOVA?

My primary question is how to interpret the output (coefficients, F, P) when conducting a Type I (sequential) ANOVA? My specific research problem is a bit more complex, so I will break my example into ...
2
votes
2answers
811 views

Collinearity between categorical variables

There's a lot about collinearity with respect to continuous predictors but not so much that I can find on categorical predictors. I have data of this type illustrated below. The first factor is a ...
7
votes
2answers
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 ...
2
votes
0answers
218 views

How to implement a weighted 3-way ANOVA in unbalanced design?

I have implemented a three-way anova with type III sum of squares in c++. Since some of my experiments (observations) are more important (more informative), I want to give them a higher weight in my ...
4
votes
1answer
560 views

The effect of the number of replicates in different cells on the results of ANOVA

I have written 3way-anova in c++. I have 3 factors, lets say a,b and c and my aim to check the strength of all possible interactions and main effects.The result of my code is the same as MATLAB when I ...
11
votes
4answers
1k views

Should I include an argument to request type-III sums of squares in ezANOVA?

I developed the ez package for R as a means to help folks transition from stats packages like SPSS to R. This is (hopefully) achieved by simplifying the specification of various flavours of ANOVA, and ...
11
votes
4answers
4k views

How does one do a Type-III SS ANOVA in R with contrast codes?

Please provide R code which allows one to conduct a between-subjects ANOVA with -3, -1, 1, 3 contrasts. I understand there is a debate regarding the appropriate Sum of Squares (SS) type for such an ...