I have these data and I want to assess the sphericity as a condition to apply an ANOVA for repeated measures.
EGPRE<-c(4, 6, 2, 6)
EGPOST<-c(7, 3, 2, 6)
EGRE<-c(6, 2, 1, 4)
What test do I have to use? Mauchly test or maybe Greenhouse-Geisser test? How do I develop them with R?