2-way anova on unbalanced dataset

Posted by mortalitysequence on Stack Overflow See other posts from Stack Overflow or by mortalitysequence
Published on 2010-04-12T19:15:01Z Indexed on 2010/04/13 7:13 UTC
Read the original article Hit count: 355

Filed under:

Is aov appropriate for unbalanced datasets. According to help ...provides a wrapper to lm for fitting linear models to balanced or unbalanced experimental designs. But later on it says aov is designed for balanced designs, and the results can be hard to interpret without balance.

How should I perform a 2-way anova on an unbalanced dataset in R?

I would like to reproduce the different results for type I and type III sum of squares of SAS output (when using proc glm). I remember we were using type III sum of squares for unbalanced datasets.

Thank you in advance.

Related posts about anova

Homoscedascity test for Two-Way ANOVA

as seen on Stack Overflow - Search for 'Stack Overflow'
I've been using var.test and bartlett.test to check basic ANOVA assumptions, among others, homoscedascity (homogeniety, equality of variances). Procedure is quite simple for One-Way ANOVA: bartlett.test(x ~ g) # where x is numeric, and g is a factor var.test(x ~ g) But, for 2x2 tables, i.e. Two-Way… >>> More
ANOVA with 3 fixed factors in R

as seen on Stack Overflow - Search for 'Stack Overflow'
Im trying to run a model with a response variable p and 3 fixed factors to get ANOVA. this is how my code looks like : #run it as 3 fixed factor model p1=c(37,38,37,41,41,40,41,42,41) p2=c(42,41,43,42,42,42,43,42,43) p3=c(30,31,31,31,31,31,29,30,28) p4=c(42,43,42,43,43,43,42,42,42) p5=c(28,30… >>> More
2-way anova on unbalanced dataset

as seen on Stack Overflow - Search for 'Stack Overflow'
Is aov appropriate for unbalanced datasets. According to help ...provides a wrapper to lm for fitting linear models to balanced or unbalanced experimental designs. But later on it says aov is designed for balanced designs, and the results can be hard to interpret without balance. How should I perform… >>> More
Power Analysis in [R] for Two-Way Anova

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to calculate the necessary sample size for a 2x2 factorial design. I have two questions. 1) I am using the package pwr and the one way anova function to calculate the necessary sample size using the following code pwr.anova.test(k = , n = , f = , sig.level = , power = ) However,… >>> More
R: including model specifications in xtable(anova(...))

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello R comrades: I have a bunch of loglinear models, which, for our purposes will just be glm() objects called mx, my, mz. I want to get a nicely-formatted xtable of the analysis of deviance, so naturally I would want to perform xtable(anova(mx, my, mz, test = "Chisq")). The vanilla output of… >>> More

Developer IT