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| R calculates sequential or Type I SS by default when using ''lm'', ''lmer'' and ''aov'' as opposed to the type III SS (default in SPSS) which partials out effects of other terms in the model. A hierarchical approach is suggested which gives the same results for both sums of squares and only looks at the highest order terms in a model. See [http://tolstoy.newcastle.edu.au/R/help/05/04/2981.html here]. | R calculates sequential or Type I SS by default when using ''lm'', ''lmer'' and ''aov'' as opposed to the type III SS (default in SPSS) which partials out effects of other terms in the model. A hierarchical approach is suggested which gives the same results for both sums of squares and only looks at the highest order terms in a model. See [[http://tolstoy.newcastle.edu.au/R/help/05/04/2981.html|here]]. |
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| [http://tolstoy.newcastle.edu.au/R/help/05/08/9560.html may be obtained] using terms of form | [[http://tolstoy.newcastle.edu.au/R/help/05/08/9560.html|may be obtained]] using terms of form |
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| for ''lm'', ''aov'' and ''lme''. The ''Anova()'' procedure can be used to obtain type 3 sums of squares for ''lmer'' in R. The Anova () procedure is available by downloading the ''car'' extension package from [http://cran.r-project.org/ here] and can be inserted into the R library folder located in C:\Program Files\R\R2.x. You can also use the summary() procedure, for obtaining type III SS for ''lmer'' from version 2.7.2 of R. | for ''lm'', ''aov'' and ''lme''. The ''Anova()'' procedure can be used to obtain type 3 sums of squares for ''lmer'' in R. The Anova () procedure is available by downloading the ''car'' extension package from [[http://cran.r-project.org/|here]] and can be inserted into the R library folder located in C:\Program Files\R\R2.x. You can also use the summary() procedure, for obtaining type III SS for ''lmer'' from version 2.7.2 of R. |
Sums of Squares used by R in lm, aov and lmer
R calculates sequential or Type I SS by default when using lm, lmer and aov as opposed to the type III SS (default in SPSS) which partials out effects of other terms in the model. A hierarchical approach is suggested which gives the same results for both sums of squares and only looks at the highest order terms in a model. See here.
Type III SS may be obtained using terms of form
fit <- anova(lm(y~x+z)) anova(fit, ssType=3)
and
model.2 <- lme(y~a + b, random=~1|group) anova(model.2,type="marginal")
for lm, aov and lme. The Anova() procedure can be used to obtain type 3 sums of squares for lmer in R. The Anova () procedure is available by downloading the car extension package from here and can be inserted into the R library folder located in C:\Program Files\R\R2.x. You can also use the summary() procedure, for obtaining type III SS for lmer from version 2.7.2 of R.