SOURCEBOOK

R | Data Analysis

Repeated Measures ANOVA

Prior to the steps below, enter the data as appropriate for the analyses (described elsewhere). As always, the following commands should be typed directly in the R console window.

Obtaining Descriptive Statistics

Get the means and standard deviations for the variables.

mean(Outcome1)
sd(Outcome1)
mean(Outcome2)
sd(Outcome2)

Change the data format for use with R procedures.

StackData=reshape(RepeatedData,varying=c("Outcome1","Outcome2"),v.names="Outcome",timevar="Factor",idvar="Subject",direction="long")
attach(StackData)
StackData
Results=aov(Outcome~factor(Factor)+Error(factor(Subject)))
model.tables(Results,"means")

Obtaining Inferential Statistics

Get the ANOVA source table with tests of statistical significance.

summary(Results)