[R] Bootstrapping Contrasts for Repeated Measures ANOVA

[Alex Baugh]

Two follow up questions from post regarding bootstrapping contrasts
for a RM ANOVA:

1. Because my data are repeated measures, isn't it true that I want to
shuffle my column heading individually for each subject (row) by
resampling WITHOUT replacement?

2. For my DV (latency) I have 3 columns of data (3 levels) for each
subject:

                  treatment 1     treatment 2    treatment 3
Subject 1      43 sec         110 sec           65 sec
Subject 2     400 sec         650 sec          430 sec
Subject 3      35 sec         40  sec           50 sec
  .                       .               .              .                 .
  .                       .               .              .                 .
  .                       .               .              .                 .


The data are nowhere near normally distributed, so I bootstrapped the RM ANOVA,
which was signficant. Now I want to do an orthogonal contrast asking if
(treatment 1) is different than (treatment 2 + treatment 3) because this is the
a priori sensible question to ask given the overall effect. If
this means I would average columns 2 and 3 I think this is
statistically wrong due to a difference in sampling?


Thanks,
Alex






Thanks


-- 
Alexander T Baugh
Section of Integrative Biology
Univ. of Texas at Austin C0930
Austin, TX 78712
http://darktropic.blogspot.com/