[R] Q about how to use Anova.mlm

pgseye prseye at gmail.com
Fri Jan 30 01:39:41 CET 2009


Hi,

Am newish to stats and R, so I certainly appreciate any help. Basically I
have 50 inidividuals whom I have 6 photos each of their optic nerve head. I
want to check that the orientation of the nerve head is consistent, ie the 6
replicates show minimal or preferably no rotation differences. I'll draw an
arbitrary line between some blood vessels (same reference in each set of
replicates) and determine an angle of deviation from the vertical and that
angle will be my dependent variable.

Subject	  Replicate	  Angle of Deviation
1		       1		       x
1		       2		       x
1		       3		       x
1		       4		       x
1		       5		       x
1		       6		       x
2		       1		       x
2		       2		       x
2		       3		       x
2		       4		       x
2		       5		       x
2		       6		       x
etc            

I'm wanting to test for Sphericity (because I've read that you should - is
this routine in a repeated measures ANOVA?) and can see that Anova.mlm in
the CAR package offers this in addition to the alternative Greenhouse and
Feldt tests.

I just don't really know how to perform the test - can someone give me some
help.

Thank you.

Paul

Dept of Ophthalmology
Uni Melbourne, Australia
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