[S] MANOVA with splus (repeated measures)

Gabriel Baud-Bovy (baudbovy@fpshp1.unige.ch)
Tue, 10 Feb 98 16:08:00 +0100


Hello,

I do have a problem in replicating the MANOVA analyses published
in statistical books with SPLUS 3.4 (UNIX version). For example, I would
like to have the exact procedure to follow to get the correct
results (F values) in the two following examples:

1) Repeated measure design in Stevens (1992) "Applied Multivariate
statistics for the social science", p.442-453
2) Doubly multivariate design in Tabachnick and Fidel (1996) "Using
multivariate statistics", p.476-483.

Questions:

1) Can somebody show me how to perform these analysis (see below for the
data)?
2) Where can I find information, examples of MANOVA analysis with
repeated measures done with SPLUS?

I have already sent my problem to MathSoft support. Thank you for your help,

Gabriel Baud-Bovy

PS: I would like to know also if SPLUS can compute the Huynh-Feldt or
the Greenhouse-Geisser adjustements in the case of repeated measures
analysis with an ANOVA (these are useful when the sphericity condition
is not satisfied).

------------------------------------------------------------------------
EXAMPLE 1: Stevens (1992) Applied Multivariate statistics for the social
science, p.442-453

DESIGN: single group repeated measure

One fixed factor: drug
One random factor: su

DATA

fname<-list(drug=1:4,su=1:5)
data<-fac.design(c(4,5),factor.names=fname,replications=1)
data<-data[order(data$drug,data$su),]
data$obs<-
c(30,14,24,38,26,
28,18,20,34,28,
16,10,18,20,14,
34,22,30,44,30)

RESULTS

note: for these data the Multivariate Test of Significance
(see Table 13.3) are:

Test name Value Exact F Hyp. DF Err. DF P
Pillais .97707 28.412 3 2 0.34
Hottelings 42.618 28.412 3 2 0.34
Wilks .02293 28.412 3 2 0.34
Roys .97707

---------------------------------------------------------------------
EXAMPLE 2: Tabachnick and Fidel (1996) Using multivariate statistics,
p.476-483.

DESIGN Doubly multivariate design

Between subject independent variables: cbw
Within subject independent variables: month
Dependent variables: wtloss, esteem

DATA

d1<- c(4,4,4,3,5,6,6,5,5,3,4,5,
6,5,7,6,3,5,4,4,6,7,4,7,
8,3,7,4,9,2,3,6,6,9,7,8)
d2<- c(3,4,3,2,3,5,5,4,4,3,2,2,
3,4,6,4,2,5,3,2,5,6,3,4,
4,6,7,7,7,4,5,5,6,5,9,6)
d3<- c(3,3,1,1,2,4,4,1,1,2,2,1,
2,1,3,2,1,4,1,1,3,4,2,3,
2,3,4,1,3,1,1,2,3,2,4,1)
d4<-10+c(4,3,7,1,6,7,7,3,4,4,6,5,
2,3,7,6,6,3,2,2,7,9,5,6,
6,9,5,6,3,6,3,5,5,6,6,7)
d5<-10+c(3,4,2,1,5,8,6,5,4,5,6,3,
1,4,1,5,7,1,1,1,6,9,5,4,
2,9,1,2,2,3,3,2,3,4,6,7)
d6<-10+c(5,7,6,2,4,8,9,5,5,3,1,6,
4,5,8,8,5,5,4,1,9,9,5,8,
6,6,9,8,7,7,6,8,8,7,9,7)
tabach<-cbind.data.frame( su=rep( paste("s",as.character(1:36), sep=""), 3),
cbw=rep( rep( c("ctl","diet","diex"),rep(12,3) ), 3 ),
month=rep(1:3,rep(36,3)),
wtloss=c(d1,d2,d3), esteem=c(d4,d5,d6) )
tabach$month<-factor(tabach$month)

RESULTS (please check in the book):

Between subject variable cbw: Wilks = 0.773 F(4,64)=2.2 p=0.0791
Within subject variable month: Wilks = 0.1987 F(4,130)=59.23 p=0.0

-------------------------------------------------------------
Gabriel Baud-Bovy baudbovy@fpshp1.unige.ch
Université de Genève, FAPSE tel. +41 22 705 97 67
9, route de Drize fax +41 22 300 14 82
1227 Carouge, Switzerland home tel. +41 22 320 21 38
-------------------------------------------------------------

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