[R] MANOVA

[Simon Blomberg]

You only have one response variable, so MANOVA is not appropriate. One
option would be to compare BP ~ Weight + Height with BP ~ 1. That would
give you a joint test of weight and height together. Since they are
collinear, that should tell you the overall effect of "size". There are
other options, most of which involve discarding some of the data. Frank
Harrell's book is a font of wisdom on this sort of thing.

Harrell, F. E., Jr. (2001). Regression Modeling Strategies. Springer.

Simon.

On Thu, 2009-03-12 at 00:20 -0600, Ding Xiao wrote:
> Hi All,
> 
> I have questions about MANOVA which I am still not sure if appropriately I should use it.
> 
> For example I have a data set like this:
> 
> BloodPressure (BP)  Weight   Height
> 120        115    165
> 125        145    198
> 156        99      176
> 
> I know that BloodPressure is correlated with both Weight and Height, however colinearity exists between Weight and Height. When I use BP = Weight + Height as the model, one is got to be insignificant. I was trying to use a BP + Weight = Height model, but not sure how to use it.
> 
> Should I use MANOVA? or I just have to do two equations as BP = Weight & Weight = Height 
> 
> Any suggestions and answers are greatly appreciated!
> 
> Ding
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
School of Biological Sciences
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au

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2.  Your deadline is your problem.

The combination of some data and an aching desire for 
an answer does not ensure that a reasonable answer can 
be extracted from a given body of data. - John Tukey.