Getting Sphericity Tests for Within Subject Repeated Measure Anova (using "car" package)

[SergeyUNL]

Hello everyone,

I am trying to do within subjects repeated measures anova followed by
the test of sphericity (sample dataset below).
I am able to get either mixed model or linear model anova and
TukeyHSD, but have no luck with Repeated-Measures Assuming Sphericity
or Separate Sphericity Tests.
I am trying to follow example from "car" package, but it seems that I
am not getting something right.

> Dataset$Sessn <- as.factor(Dataset$Sessn)

> LinearModel.1 <- lm(Response ~ Sessn*Trtmt, data=Dataset)

> summary(LinearModel.1)

All, good so far, but I have problem understanding "idata=" and
"idesign=" functions pertaining to my example. Session is my repeated
measure (Sessn 1 and Sessn 2 = two sessions, in reality I have more)
and it is already stacked. Any help or guidance on this matter.

Thank you, my mock dataset is below. Each subject has two levels of
treatment throughout four calendar days which are recoded to Session 1
and Session 2 in order to compare treatments by the first and
subsequent days of exposure (Treatment x Session; my DV is Response;
Session is repeated).

Subj Trtmt Sessn Response
1 N 1 5
1 D 1 6
1 N 2 4
1 D 2 7
2 N 1 8
2 D 1 9
2 N 2 2
2 D 2 1
3 N 1 4
3 D 1 5
3 N 2 6
3 D 2 2
4 N 1 5
4 D 1 6
4 N 2 4
4 D 2 7
5 N 1 8
5 D 1 9
5 N 2 2
5 D 2 1
6 N 1 4
6 D 1 5
6 N 2 6
6 D 2 2



Sincerely,

Sergios Charntikov (Sergey), MA

Behavioral Neuropharmacology Lab
Department of Psychology
University of Nebraska-Lincoln
Lincoln, NE 68588-0308 USA

sergioschr-at-gmail-dot-com